If you are entering contests you should have a good idea about what you are submitting. Some times this just takes experience. Enter often & see where you land & then look closely at those who faired better. You should be looking at two things. Were their images technically better & were they artistically better. Be honest with yourself & see where you need to improve. Develop your own style & try not to copy what has already been done. Find a new perspective, a fresh look. Work on knowing all aspects of your camera & the lenses you use.
The tree you present looks like you walked up to it, pointed your camera up & took the shot. It is a tall tree, is that what you wanted to say? I'm not trying to be hard on you, but this is what I see. I love images of trees & they can be very interesting to photograph. I see a tree that speaks to me & I may work on getting it right for years. Or I may have an idea of what I want to photograph(trees) & look for a very long time before I find it & than I may have to come back to it many times before I get the right conditions to photograph it.
I will include an of example if it helps. The Aspens were located on Boulder Mtn, in Utah. I knew what I was trying to find but after 4 trips there I decided to go in winter & try again. The mountain has lots of Aspens on top & I knew I would find what I wanted there if I could keep searching. Below is what I finally came up with on my 5th trip. By the way I live in Montana. I will also add one from Bitter Springs, Arizona.
Hope this has been helpful.