It's probably my imagination, but it felt like I was getting better enemy patterns when I selected star 3, instead of star 6. I probably only gave each star like 10 tries though, so if anything that was probably coincidence.

I failed to get a several second timesave, where you jump into the bullet bill as you land in the last area. That makes the next bullet spawn sooner, so you could hit the glass dome that much sooner.