I'm not too big on trees myself. But here's your solid critique
1. Your small branches are too thick, and almost all the same length
2. Your small branches are parallel to each other, trees are not always so even
3. Your branches have no shading
4. Your tree's shadow does not match
5. The whole thing looks like multiple radio antennas sticking out of a brown uprising
6. And your small branches should be pointing more towards the end of the big branch like in this picture.
If you heed my advice, I would like to see your progress