A few considerations before you decide on a path forward;
-Painting your entire body will not only be time consuming but also fairly costly, as any decent body paint isn't really cheap. So consider your willingness to sit still for a few hours and the cost of doing the whole body every time you want to costume. However, if done correctly (READ: Airbrush) it can be a great costume.
-Another option, consider breaking up the paint application with other costume parts, such as a Fantastic Four suit.
-If you do a green bodysuit / paint combo be sure to match the color perfectly or break up the shades with other colors to blend the green. Example: match your body paint to your suit and then use the purple/white leotard She-Hulk is known for wearing from time to time which will hide the differing shades of green on the suit and your body paint.
Just a few things to consider.