buy a big bag of rocks at Home Depot, and then rinse them under water quickly and let them dry in the sun. To prep them, I paint the tops of them with white house paint. The rocks are porous and you could spend all day trying to cover them with regular craft paint. Once the first coat of white paint is dry, they will be ready to paint with acrylic paint and a variety of brushes.
PAINTING+ON+STONES+IS+A+CRAFT+THAT+ROCKS! Great site! Gives tips and ideas with instructions on how to create designs and what mediums to use for whatever stone you want
Hand Painted Stone Flowers / Set of 7 by ISassiDellAdriatico https://www.facebook.com/ISassiDelladriatico/photos/a.486417961437351.1073741828.486411464771334/814226471989830/?type=1&theater
Painted Snowmen Lake Superior Stones 5 by TheTroveShoppe on Etsy
cool 99+ DIY Ideas of Painted Rocks with Inspirational Picture and Words http://www.99architecture.com/2017/03/28/99-diy-ideas-of-painted-rocks-with-inspirational-picture-and-words/
painted rocks - kiwi, orange, strawberry, watermelon by Judy A. Kibler