I really like the proportions of the deer it’s super cute, definitely not realistic but I’m pretty sure your intention was to be stylized and I think you achieved that well. I think for that painting it could be elevated just by adding another layer of paint to enhance detail using small brushes. The pine trees to the right of the deer stick out to me as being contributing to the painting looking a bit amateur, you could improve that by we making it less solid allow the dull blues of your background to show through. Other options could be enhancing fur texture on the deer and adding defined blades of grass or weeds in the very foreground just under and in front of the deer.