I don't consider myself even a mediocre photo bug. In fact, I struggle quite a bit. Some things have helped my photos - First, I shoot on a light absorbent material, to reduce reflection of the light (I'm currently using velvet). Second, the first picture looks like you need to move the light outside of the tent more towards the front (the one on the right side). There seems to be shadow on the right side. The second pic looks too dark and the third seems to have too much reflection on the background.
Hope that helps, it's all I got!