I carved the stamps as they were finishing up watching cartoons this morning, so when they ended we were ready to go!
We have these handy paint smocks, which have saved their clothes on multiple occasions and just used regular printer paper.
(ok, little guys stamps turned more into finger painting... and we only have 2 painting smocks!)
We found it worked best if you just spread a small layer of paint on the stamp (instead of dipping in the paint) but it probably depends on what kind of paint you use. We used regular poster board kids paint, it's pretty thick.