Heavy - We should first talk about this, the "bad" keyword. It is the only keyword that is not a benefit to you, ever. Your squadron is no longer capable of locking down enemy squadrons, keeping them from moving. That is not to say you are not engaged - you certainly are and gain all the benefits and downsides that come with being engaged. Two Heavy squadrons that are engaged with one another are just that - engaged. You tend to see these on bombers, and larger slower transport squadrons like the YV-666 or VCX-100.
If you use a Heavy squadron, keep in mind you will need other squadrons to pin your opponent's fighters and bombers in place.
Bomber - This gives your anti-ship dice the ability to resolve critical effects (specifically the standard critical effect) and lets you count critical results as damage. For the most part, this is a good designation for a ship that will excel in an anti-ship role, though sometimes that is secondary to their actual purpose (see X-Wing / E-Wing / Dash Rendar). Any one of them though can benefit from Bomber Command Center.
You want your Bomber squadrons to clear the fighter scrum and engage enemy ships, weakening them for your capital ships or finishing off wounded ships trying to escape the engagement before they can get away. In the past, this meant holding them in reserve to try and sneak them around the fighter scrum, or using other fighters to break them free, but now involves using Intel to move them away from an engagement.
Escort - These squadrons are there to protect more important squadrons. First, make sure you know what the more important squadron actually is. For example, Darth Vader makes a poor Escort, because there are few squadrons more valuable to you than Darth Vader. Likewise, Luke Skywalker doesn't want to keep your opponent from firing at a 10 point, 6 hull Y-Wing. This is counter-intuitive, I know, but make sure your Escorts have something to protect, or rather, if you are taking something worth protecting, make sure it has a proper Escort. Intel squadrons are a perfect example of this, as our low-hull, valuable elite squadrons.
Escort squadrons should sit in front of what is important. That does not mean in front of the entire deployment, just what is important. Say you have a Bomber force of Y-Wings, and a pair of Intel ships. Your deployment should be massive wave of Y-Wings > Escorts > Intel Ships. You want those Y-Wings engaged and shot at - that's why you brought the Intel, right? Conversely, you also don't want the Escorts shot at immediately, not if you can spread the wealth to a cheap 10 point, 6 hull monster.
Alternatively, let's say you have a bunch of A-Wings, but also some X-Wing Escorts. Engage with the A-Wings, and when your opponent retaliates, you get your Counter attack. Now your A-Wings are injured. Move up your X-Wings to protect the injured A-Wing, but leave other undamaged A-Wings open to make more Counter attacks.
Counter - The opposite of Escort, you want to trick or force your opponent to attack this squadron, so you can get free damage in if they are attacking someone. This works excellent as a Bomber squadron Interceptor, in fact the best Counter squadron is actually the TIE Interceptor. You'll see these on the best Interceptor role squadrons - the TIE Interceptor and the A-Wing. You'll also see this on some slower ships not intended to be interceptors as a sort of additional defense, including the YT-1300 which combines Escort with Counter for excellent fun. For Imperials, Dengar can be used to give the keyword to your own Escorts, for similar results.
That's it for Wave 1 Keywords. Look for Waves 2, and Wave 5 keywords in a later article.