Model rocket How to achieve max. altitude? (w/out altering engine)

[rocketnoob101]

I am building a model rocket for a school project, and I am using a PITSCO model rocket kit. We are not to be altering the engine in any way. What can I do to get the highest possible altitude and maximum time duration? (from launch till touchdown) As far as I know, the best thing we can do to keep it going straight and as fast as possible, is to make sure the three fins are the exact same shape, and are all attached to the body tube as straight as can be. Any other ways we can achieve maximum altitude? Besides slimming it down? Thanks!

 

[rocketnoob101]

fins

I have read that low drag clipped-delta fins are the best type for stability in a rocket like this. I need to know what the dimensions are for these fins, if anybody knows... The material I am using is 1 3/4 inches wide, so it cannot be any wider than that. Any help would be much appreciated, thanks.