Another good tip is to sand and scrape off the obvious seams so that they are not on your finished model. Doesn';t take TOO long to do, but makes the finished product so much nicer.
Also prep the model with a good primer (Krylon in a shade close to what the final coat color w/b if possible) to help the new coat last.
Use acrylics for best results w/kids as the pigments are all safe, etc. (check the labels) and USE RESPIRATORS for sanding, for spraying primer and sealant.
Krylon matte satin sealant/clearcoat is best for spraying over top of your finished paint jobs, and then take clear gloss nail polish and go over the eyes to give them that real life, liquid look. Also hooves if you want them shiny.
I have a few links for you to look at if I can find them....
Liz M>