The strategy guide lists exactly the play-by-play for that section to perfect it, like exactly what order to shoot each moon and how long to charge up your laser. If you want to get the achievement for it (can't remember if it's for no damage or not) you can look into that. The guide in general was very good.
Also if you're going for achievements, the Squashtrich one is kind of weird. You can't die and choose "retry" because even then, if you don't take any damage, you won't get the achievement. You have to entirely reload for it to let you get the achievement. That made me very tilted