Hard to understand at first, but when you do, it gets more interesting.
I struggled the most with the flowers.
Tree Solution: The flowers from left to right are: 1, 2, 3, 2, 2, 1.
Moon Solution: From small to large. Click on the craters in order!
Cloud Solution: Make every cloud white.
Mushroom Solution: The colours from left to right are: blue, red, orange, green, purple.