It is not intuitive but it makes sense once you choose the primary weapon that drops bombs from the end of your tail. You need to be able to manoeuvre it between the enemies.
Alternatively you could make segments flash when they come in contact with enemies and start flashing red when they need a cool down before you lose the segment.
I noticed most of the games where I made it to the end I scored around 470k, one time I scored 894k but I can't remember what I did differently.