Basically our strikers lack aggression. When you don't have the skills, you MUST have the brawn!
Look at rooney, look at Tevez, they fight with or without the ball. If you know that you are not the kind of striker to score 1 goal from 1 shot, then you jolly well work hard and create 10 shots for yourself, and hope that one will go in.
I used to play for my school team and I had similar issues until i upped by aggression, then the goals started coming in, together with the cards of course heheh. But, defenders will hesitate when coming near you and that makes strikers job easier. I know I will never be able to dribble the whole team or score from a first touch acute angle, but I make sure I force my way into good scoring positions. I always set aims, to win at least 5 tackles, to get at least 5 shots, to get at least 4 players falling or wincing on the ground from my shoves.
None of our strikers seem to try that hard.