>>1951708For the hand, here's how I'd do it (see picture). I generally use that technique for skin and long hair, it helps with the awkward curves. Hands, fingers and nails are pretty tricky so you might need to fiddle with them a bunch.
For the thickness, there are a few areas that could use some touching up but in general it looks much better. I've circled them in red in the following ai file.
https://www.dropbox.com/s/k2nvjft995wlop8/Hotaruexample2.ai?dl=0 