Beginner's Guide to Ships

Crew are the primary contributors to your ship's stats. Everything about them matters - gear, stars, level, mods (to a minor extent), and even ability levels. However, regular stat differences don't matter - only these 5 things listed here. Some aspects help more than others, and the higher you go in any one area the bigger the difference (going from 6 to 7 stars has roughly the same impact as going from 2 to 6 stars).
Something of note that many seem to miss: Mods do NOT affect ships the same way they affect characters. Only the tier and level of the mod matters; primaries, secondaries, and set bonuses do not.
Watch out: crew power != crew rating. Crew rating, which is what the game uses to calculate your stats, is hidden and based off the 5 character aspects. Crew power is just an estimate of crew rating.

This debuff is central to ships. Target locks should be kept in mind when building a fleet. If you want to use ships that need target locks for powerful effects (Umbaran Starfighter’s missile attack, for example), make sure to include a few sources of target locks so you can access some extra utility and damage.

Home One is the middle of the road capital ship. It provides both offensive and defensive boosts, but arguably not as well as the other two non-legendary capital ships. Its two assist-generating attacks (basic and AOE) add extra damage to the fight while the protection up it grants to assisting attackers can provide a good deal of sustain. Ships like Geonosian Soldier’s Starfighter and Jedi Consular’s Starfighter are recommended for the additional assists.

Executrix is the full force offense-oriented capital ship. With Expose on its basic, the ability to give Offense Up (one of the only sources for the buff), and an "ultimate" that hits 12 times, all the Executrix wants to do is blow up the enemy as quickly as possible. Combining the Executrix with all the various Empire ships will maximize the damage and turn meter bonuses.

Endurance is the defensive counterpart to Executrix. With a taunt that can go on anyone and the opportunity to get full damage immunity for one turn, the Endurance is the definition of a tanky wall. It synergizes best with Republic ships, though fleets with a non-Republic focus can still work (i.e. target lock teams centered around Endurance’s AOE). Using another taunt and one or two healing abilities, you can rotate taunts around to keep the enemy wasting damage while you whittle away at their ships.

Reinforcements are a fun and strategic feature in ship battles. Since you get to see your opponent's starting ships, you already know what you want to bring, but you can't know exactly how the fight will turn out. Reinforcements let you pull in a single ship at a time when you lose one of your current ships, and this enables you to adapt to the circumstances. However, you probably don't want to just stick 4 random ships there, even if they're the next best four to your starting fleet. Reinforcements enter battle with 100% turn meter, taking a turn right away, but at the expense of your capital ship's action. As such, reinforcements should be brought in intentionally, not necessarily immediately after a ship dies (though that's usually when you would call in another ship). Additionally, not all ships have the same impact when coming in from reinforcements. Some benefit a lot more than others from activating immediately without the enemy having a chance to shoot down or block their options. Do note that ships waiting in reinforcement don't count as part of your active fleet and don't have to be destroyed in order for the enemy to win.