#1, peel the backing off! I know, it sounds silly, but a lot of people have done it. Especially on econokote. Econokote and towerkote both tend to shrink first, then stick! (that's why it it CHEAP...)
Cut it oversize. tack down all four corners w/ the tip of your iron. then do edges. then shrink centers. Don't have the iron too hot, or it will shrink like crazy but not stick.
solid surfaces like fuse. are actually easier than wing. do bottom. sides. then top. have iron just hot enough to stick it, and work it around. I wouldn't paint it, just keep at it, observe how it behaves, and you will figure it out.