1. Absolutely get there early -- before opening
2. Learn about and use FP (HydroGuy has written books on the subject; search for his threads)
3. Think about your meals ahead of time. It's not hard to waste an hour in line waiting for a burger if you go to a counter service place like Club Buzz at 12:00. You'd be better off eating at DCA and/or off peak times.
4. I agree with most of what DL29 says, except that you can get more FPs and get in more rides before heading over to DCA. Remember, you can use FPs later than the time shown. And I might throw in some shows (Aladdin, Steve Martin's 50th movie, a 3-D show; those are good midday when the lines get line to the rides). Try to catch the fireworks if you can.
5. Keep in mind that not all teenagers will do thrill rides. None of the rides at DL are too intense, but some people just don't do coasters or big drops. You might want to break the kids up into groups according to the thrill factor.
Just last month, I went to DL with my teenage thrill ride lovin' son, and his BF who loves DL but does not do coasters or big drops. We had a fabulous time, but we split up at times so that we could all do the rides and shows that we wanted to do.
My must-dos for just about everyone:
DL: Buzz (FP), Pirates, HM; Peter Pan (early -- even before Matterhorn -- or at closing; very low flow rate) Fireworks
DCA: Soarin'(FP) and Aladdin (show) if you've got a chance
Must dos for everyone but the timid
DL: Splash Mtn (FP, very long lines without FP), Indiana Jones (FP), Matterhorn (no FP, must do early)
Also recommended: BTMRR
DCA: Grizzly River Run (you'll get wet) (FP - Disconnected; which means you can get one even if you hold a FP for Soarin')
Must do for the fairly brave (including most teens)
DL: Space Mtn (FP); DCA: ToT (FP), Screamin'
Teens also like:
Star Tours, Teacups, Roger Rabbit (disconnected FP), Autopia (FP)
I'd try to throw in Jungle Cruise since its such a classic.
I'm sure I'm missing a few things.