I have not gotten very far. But, hopefully these tips can help the people who are struggling with the game. First let me explain a bit about your weapons. You fire 2 torpedoes from the sides of your ship in a straight line for 3 spaces. They travel through asteroids and space debris (what is left after a drone dies) and as far as I know, all enemies take 1 torpedo before dying (except comets, they are invincible).
Second are the little gem things. There is one on every level (If there is not one on really high levels, please, let me know) and some are more valuable than others.