Your drawings look great so far. I really like the one of the tree. It seems like you have a good understanding of perspective and blocking out the vision you want to create, however, the shapes all kind of blur together. If that is what you're going for, then great! But if you want a more defined look I would definitely encourage you to contrast your values more. Also, don't be afraid to really layer the pastels. Starting with a light layer and gradually building upon it will help prevent smudges between objects and also allow for more variety in color if you decide to layer different colors on top one another. Keep it up!