Perhaps you would like more contrast even if it's just color blocking, just so you can visualize things better while studying.
For complex tridimensional shapes, I suggest always starting with pencil on actual paper, breaking down shapes into primitives such as cylinders for the phalanx and spheroids for the finger tips and the palm pads.
In this take, the middle finger is a little too curved considering the index finger is more relaxed. It so also looking a bit noodle like instead of divided into finger sections, but that can be a consequence of the (still) small scale for that amount of detail.
It could very well be this curved but then ring finger would be more clawed as well, since these fingers tend to no be so anatomically independent of each other unless forced into positions.
Keep it up, it's an often repeated saying, but hands are hard, I have a lot of trouble with that.
