Painting skin weights tool....

For adding influence I have been using the Add option in the tool. If i know the influence is needed throughout i add to the value of 1.

Some of the geometry is needed to be slightly influence by others so i use half the value of 1 or .3 to influence the verts in the right places.

If influence needs taking off i use replace at the value of 0. - However using this adds other influences from other joints so it can make the geometry worst then needed.

When i have all of the influence needed i smooth them over using the flood tool under smooth. If you work from the outside or more influenced down the joints i fid this can work best.