++Starting Battlefleet Gothic: BFG Rules and Fleet Basics++
Before you start Battlefleet Gothic (BFG), you should know a few things...
-BFG has a few sets of rules that are commonly used: 1. the GW rules listed on their website, 2. the 2010 FAQ rules (still unofficial), and 3. BFG:R is a revised set of rules (also unofficial). I, personally, like BFG:R the best (I think it is the most balanced, interesting, and supported), and also FAQ 2010/2010 Compendium (I don't like it as much but it tends to be the most widely used). For full disclosure, I am a supporter of BFG:R and believe in the project. However, I do not have a say in the rules. That being said, most of my comments below apply to all 3 rules systems. If there are specific comments that need to be made for one of them specifically, I will mention it.
Game Phase Basics:
Movement: The movement phase in BFG is amazingly important, not just for getting in range and out of range of ships you want to avoid, but setting of the night firing arcs (which makes a huge difference in this game). Firing on a closing ship with your weapon batteries is WAY more powerful than if the enemy ship is abeam (of has its side) to you. Also, range matters. Over 30cm and you are long range; under 15cm, you are close ranged. This makes a big difference. Getting the right positioning to hit the enemy from the most advantageous point and being in a place where the enemy either has to move and shoot you from a bad angle or have to use a special order to hit you at a good angle (which reduces their firepower) is a huge part of the game. Many fleets, as you will see below, are much more maneuverable than others. This is a huge advantage. Understanding how to use the movement phase to your advantage takes time and is one of the challenges of the game. Also, this is the phase where you can "disengage ships" that are on the verge of destruction. Knowing when to get your vessels out of there before they go boom is an important judgment call. Ramming also takes place in this phase, with some fleets excelling at it and others needing to avoid it like the plague.
Shooting: After moving your ships, you get to fire your weapons at the enemy. Determining which ships should be fired at, with what weapons, and in which order, are important decisions. Most will recommend firing your weapon batteries before firing your lances (as would I). Having a variety of weapons in your fleet is usually a good idea because some weapons work poorly against some fleets (weapon batteries against Space Marines and Necrons, for example). Knowing when to try to get an enemy ship to brace for impact (thereby reducing their shooting against you the next turn), allocating enough firepower to cripple the enemy ship (permanently reducing its capabilities and earning you victory points), or going for the all out kill (obviously ending its shooting at you and earning you full victory points for the ship) are tough decisions and you will need to learn how to weight the benefits and drawbacks.
Ordinance: This phase is where you will be able to utilize your torpedoes, fighters, bombers, assault boats (bomber sized boarding vessels), and more. This phase becomes a mini-game within the game (which is amazing). Bombers and assault boats can do tons of damage to enemy ships but are vulnerable to enemy fighters (even more so in BFG:R where fighter squadrons can kill more than a 1:1 ratio of bombers and assault boats). When planning a fleet, you will have to consider how you will defend against ordinance; it is a necessity for having a powerful (or even decent fleet). When a ship is attacked by bombers, assault boats, or torpedoes, it can use its turrets to try to kill some of the ordinance off before it is hit by them. Some fleets have a low level of available ordinance but high levels of turrets. Be mindful of this when making your fleet list and make sure you have a way of defending against at least average ordinance.
End: In the end phase, a few different things can/do occur. First off, boarding actions can happen when you are in contact with an enemy ship. Many fleets have great boarding and some have very poor boarding. Make sure you remembering the possibility of being boarded. Another thing that can happen during the end phase is teleport and hit-and-run attacks. These attacks are basically the equivalent of mini boarding where you are either teleporting or deploying troops onto the enemy ship. This will mainly kill the smaller escort class ships or cause damage to larger ships, mainly in damaging their weapon systems. Also, blast markers (which mark explosions and debris on the battlefield) will be removed following the black marker removal rules. Finally, critical damage (damage to weapon systems, etc.) can be repaired in this stage.
(all of these are written in my personal opinion and it is worth getting as many experienced opinions as possible. Names of fleets that are clickable will lead to tactics articles on that fleet.)
Imperial Navy (IN): The main strength in the IN fleet is their heavily armored prow and the amount of torpedoes they being to bear. They also have the capability of wielding the long range Nova Cannons. The IN has tons of options and is one of the most commonly played fleets. The weaknesses of the IN are that they are relatively slow, have average leadership, and boarding.
Chaos: Chaos are extremely well armed, are relatively quick, and have lots of long ranged weapons, especially on their broadsides. They have the capability of bringing lots of launch craft to bear to complement their long ranged weaponry. They have lots of options was well and are able to make a very capable head on fleet or a side-strafing fleet that focuses on broadsides (my personal choice). They are one of the two most played fleets. The weaknesses of the Chaos fleet are their lack of torpedo carrying ships (they have a couple) and only average armor all around.
Space Marines (SM): The Space Marine fleet is one of the most durable fleets in BFG, with mostly 6+ armor all around. They also have Bombardment Cannons (kind of like a mixture of weapon batteries and lances), and their torpedo ships can all fire boarding torpedoes (which is really nice for incapacitating ships and destroying escorts). They are fast, reasonably maneuverable, and have the highest leadership possible. Also, they have Thunderhawk Gunships which are great fighters and can also be used as assault boats. Their weaknesses are a major lack of lances, usually a smaller amount of ships, and Thunderhawks are the only launch craft you get and they are somewhat slow. As a side note, FAQ 2010 and BFG:R provide bonuses for whichever chapter you chose to be, which I think is a really nice touch.
Adeptus Mechanicus (AdMech): The AdMech fleet is essentially a more expensive and limited IN fleet but each cruiser/battleship comes with an extra lance and each ship gets an upgrade from the AdMech ship upgrade list. Depending on the rules list you are using, the upgrades may be random (BFG regular, FAQ 2010) or purchaced (BFG:R). This is the fleet that should focus on long range and Nova Cannons. Every cruiser has an additional 60cm(!) lance on top and they have the highest possibility for Nova Cannons. These facts combined and having a 6+ prow make for a great front facing, long ranged fleet. Not to mention, they have pretty high leadership. Their weaknesses are in their price (even more in BFG:R), their randomness (only in BFG regular and FAQ 2010), and their very low number of ships.
Corsair Eldar (CE): Of the Eldars, CE have the most options. Most players have abandoned the original Eldar rules in favor of the MMS rules, which balance out the Eldar fleets verses other fleets (they used to be terrible against some, awesome against others). CE have great weaponry and launch craft. They are amazingly fast and highly maneuverable. Every weapon they have is better than the normal version. CE fleets should be escort heavy because of how amazing they are. A common fleet will have 1 Void Stalker, 1 Aurora, and all escorts after that. Their weaknesses are that their guns are short ranged, almost always shoot only in the front arc, they are fragile, and are dependent on the sun for their speed (which makes it a little harder to maneuver).
Craftworld Eldar (CWE): CWE are very similar to CE in that they have the same weaponry besides a few things (Phantom Lances as opposed to Pulsar Lances). The MMS CWE are much more widely used (from what I can tell). Most people believe that they are best used as a balanced fleet with some escorts thrown in there (the only type they can have), some Wraithships (used with lances and torpedoes is a popular configuration), a Dragonship or two, and a Void Dragon/Flame of Asuryan. They have pretty good leadership and some nice upgrades you can get (not to mention the not so often used Ghostships). Their weaknesses are about the same as the CE but they also only have 1 type of escort (two really).
Dark Eldar (DE): DE are much like the CE and CWE lists except they do not have solar sails (and are therefore not dependent on the sun's facing), have Impalers (which are great), have leach torpedoes (which some like), have mimic engines (which vary depending on the rules set), and have only a couple ships which each have different gun options (more choices added in the BFG:R list). Their weaknesses are much like the other Eldars; they are fragile with great firepower so they must be cautious how and when they attack.
Orks: Orks are durable on the prow, have random firepower for many of their guns (may be weak or may be very powerful), can have a whole bunch of torpedoes, have ram ships, have fighter-bombers, and can automatically go on all ahead full special orders. Their weaknesses include very low leadership, slower (but automatic) all ahead full, and fragile afts.
Tau (Forgeworld and Specialist Games Tau): Tau fleets have above average prow armor and mostly front facing weapons, which makes them a great head on fleet. Generally, Tau like to close slowly because they have the fastest torpedoes in the game and their torpedoes are amazingly accurate because they can turn every turn. Their bombers are great and their ordinance capabilities are awesome. Mainly, their drone-controlled torpedoes are their selling point. Their weaknesses are they have relatively lower hit points, are awful at defending against boarding actions, and have less than average broadside capabilities. Side note: ordering Tau ships for Forgeworld is usually cheaper than ordering the pewter ones from Games Workshop and, in my opinion, are much better looking with similar rules.
Tyranids: Tyranids are highly evolvable. They have a couple different ship types which can be armed with a bunch of options. They have the capability to have a massive amount of assault boats and fighters on the table. Their weapon batteries and lances are better than the standard versions (though mostly with lower range). Tyranids also have amazingly high boarding values and can overwhelm enemies quickly. Their weaknesses are their spore clouds (instead of shields), low weapon range, "all is lost" (enemies can chose to self-destruct when they are boarded), synaptic control, and mandatory hive ships (pretty much).
Necrons: Necrons; the "overpowered" fleet. Necrons have amazing firepower, with most of their guns being better than the usual type. They are the most durable fleet in the game (arguably), are able to repair better than most, can destroy ordinance well without fighters, are able to disengage at will, and have an amazingly powerful all ahead full special order. Their weaknesses are the lack of ordinance (they have none), no shields (kind of made up for by their auto-brace for impact), and their PUNISHING victory point chart. Necrons are overpowered if you do not use the victory point chart that is build to counter-balance them.
(I consider these secondary factions because they are either very small or are meant to be added onto other fleets)
The Inquisition: The Inquisition list adds 2 ships that can be used with Imperial Navy ships (Blackship and Inquisitorial cruiser). There are some benefits to using this list, mainly the Inquisition upgrades that can be taken with an Inquisitor. There really aren't weaknesses to this list other than it costs points to use the upgrades. Side note: the Inquisitorial cruiser is amazing. It's like a cruiser sized Strike Cruiser.
Rogue Traders: Rogue Trader fleets are similar to IN and Chaos fleets but each ship have different technology upgrades that can be taken. They can take ships from IN and Chaos lists and have a whole bunch of upgrade possibilities.
Demiurg/Kroot: Demiurg have laser technology that are over-charged by the energy of blast markers. They have powerful front armor and lots of firepower. They are fragile as far as hit points goes, and need to be careful to not get overwhelmed.