At this level it is really essential to avoid as many Spider Bubbles as possible. I started out with bursting clusters with spider bubbles in them right away in the beginning when they had only a few spiders that they could send back up. This was the perfect solution!!! =) Remember to maximize the use of the bubbles left(have max 20 when the ceiling breaks) in the cauldrons when the ceiling breaks. That way you can guarantee yourself at least one star, as you have a lot of yellow and maybe some green spiders to drop the remaining bubbles on.
Luca made a great level 1, thank you very much!