Try not to accelerate quickly. Maintain constant speed as much as possible. If stopping for a very short period of time (less than a minute) don't turn off the engine. Starting the motor is the equivalent of letting it run for a minute at idle (approx.). Use your brakes instead of down shifting. Supposedly using the AC vs. opening windows at highway speeds gives you better mileage, in my experience this hasn't had nearly the effect I was lead to believe it would. Alignment. Supposedly not running your electrical system will save you gas, since you aren't diverting as much engine power (or so I'm told, I don't really believe it though...). Another one which you may consider is having the VTEC engagement point changed to a higher RPM.
EDIT: Forgot to mention, don't fill your tank up all the way. Goes along with the reduced weight thing. By only filling up my tank (2000 EXV6) to half, i get between 1 and 2 extra mpg.