All you need to do is get every single point possible. It is a relatively easy level. I would suggest doing some spins at the beginning and end of the level to get some extra points just in case you miss something.
Lvl 2 Beloved Cheese
If you get everything you should be good. It helps to jump on the ramps sooner because you get points for how long you are on the ramp.
Lvl 3 Pits O' Goodies
This level mainly consists of trees you need to jump on. There is a group of three trees and the five trees later on in the level. Jump on the first tree in each set so you hit 2-3 trees instead of only one.
Lvl 4 Scoring Flag Combos
To 3 star the level you need to get all 5 flags in order to get the flag combo. In order to do it you need to get the final flag which is behind a tree at the end of the level. To do this, jump early, instead of later, so he can barely clear the tree and get the flag. The tree is not necessary to 3 star the level.