I'm sure others will be along soon to also give input....
the Boynton area is one of my favorite areas to dive in South Florida. You'll most likely encounter reefs with up to a 15 foot ledge, with lots of holes and crevices to peek in--often, turtles will hole up onder them for a rest--I find a small light is always handy.
Obviously, be prepared for current--can be almost non-exisistant to pretty kicking--if it's really moving, there's no point in fighting it; just stay on the reef and let it move you.
The dive boats differ in how they work, but either they will:
-have everyone in as a group, with a DM leading with the float ball. This way, just keep him/her in sight and stay with them--they will also be able to spot hidden critters that you may not. Or
-Have buddy groups go in with their own float ball. You and your buddy will carry your own ball, which, if the current is going, can get a little tiring/annoying. It will pull you along faster than your buddy, so, whoever is not carrying the ball should stay with the person who is. The boat will come pick up each group as they surface.
The dives are generally between 55-75 feet or so, so you do need to keep an eye on your bottom times.
Otherwise, have loads of fun and see lots of good stuff!