Bypass the mini-boss in stage 6: 

In stage 6 (Zelos's fortress if you're playing Salamander or the brain area if you're playing Life Force),
there is a mini-boss section consisting of multiple boss ships that fire sets of 4 lasers. 
Move your ship all the way to the top of the screen and you will be safe until this section ends.
This glitch does not work in the Japanese re-release version of the game (the one with a purple background in attract mode).