First off, you have too many polygons! That alone will make working with body parts difficult. Here is the hand I made with C4D some month ago. Note that hand is low poly; the lower image shows how it looks like under HyperNURBS, or Subsurf in Blender. You can always generate fine mesh with modifier. Keep it simple.
On low poly hand, you can see how I consolidated vertexes to reduce number to flow into the arm. You need to do that. They say it is bad to create triangular mesh but here I was trying to use triangular mesh to create the mesh flow.