That first delfino square one is real hard for me, I keep falling in the water.
Sky Garden: If you don't have a mushroom, then mini-turbo and R jump from the ramp on the right over to the track. (This is the ramp to the right of the speed boost with an item box floating in the air)
If you have a mushroom, go to the LEFT of the speed boost with an item box floating in the air. Instead of turning the corner, go straight and mushroom and R jump over the track.
Do cloud hopping near the end of the lap.