One thing that I think is very important that I haven't seen posted yet is stretching. We think of it in terms of running or other exercise, but isn't that what we are doing here?
Limbering and stretching the fingers, palms and wrists is very important for building up the ability to play for longer periods of time without developing cramps or burning out the muscles . Stretching will give you greater flexibility and reach. When you get to a chord that requires a note that's five frets down from your first finger, you'll be glad you did!