Stay in good position and look for good openings to take your attacks.

You probably avoid trying to force legs in on a guy when it sounds like you haven't ridden legs much competitively. I'm not saying you should be scared to throw them in if the opportunity arises (double leg to a turk finish, etc) but I'd be apprehensive about trying to put them in off the whistle on top in an important match when you lack experience (its an easy way to get pinned or caught)

If he's really scared of having legs thrown in (a lot of HS kids are because it hurts when done right..), faking the motion of an attempt to throw them in can be very effective in breaking guys down because they over react while trying to prevent the leg from coming in making it easier to force their movement.

I would say that if you have better technique than he does the best thing that you could do would be to focus on what you already do best. What are your favorite moves from the top, bottom and neutral? If you stay in good position and don't make any serious mistakes (like throwing yourself to your back or getting pulled over the top on a leg ride) then technique will win over strength.