I found it helpful using zspheres in Zbrush, dynamesh, and zremesher to make some rough hands to work with. Hope you find these images i made helpful.
here using zspheres to make each finger. (used duplicate to reuse old zspheres, used ctrl+move to reposition fingers from root zsphere)
used dynamesh to combine the zspheres (needed to start from an existing shape to merge them, here i started from a couple inserted spheres)
i used claybuildup (helps to add little bits of clay) and trim dynamic (helps to make things more smooth) to try to form the knuckles and thumb a little better
used zremesher start with half and adapt. then used the zremesher half about 3-4 times to reduce number of edge loops.