This is a response to Sansceo who asked " Do you use a stylus in Photoshop while painting? I tend to get mouse-hand when doing a lot of detail work."
When I first started painting in Photoshop I used the mouse. I did a number of paintings that way, and yes, my hand would also get sore. I also found that I had no control over the width of my brushstroke unless I changed brushes. About a year ago I bought a 6x8 Wacom tablet, and it has really made the difference. There are a ton of settings that you can adjust (which can also be mind numbing). In the end I am glad I bought it. It was about $350 and has been a steady workhorse. I still use a mouse for all other applications though. I am not a total convert.
Thanks for the question.