The combination of green and yellow gives the meadow a fresh and lively atmosphere, and the small details of the picnic make the scene warm and pleasant. In the next landscape paintings, paint the trees that are further back with dark green and even dark purple colors and then apply a few light green spots on them, this will increase the depth of the painting. And bring a little light on the tree trunks, for example, you can mix a little yellow with brown after brown to get a light color. This will give your tree trunk volume. Keep going and good luck...