I have all of Lin Wellford's rock painting books. That lady literally rocks! I love all her creations and I love that anybody can paint on rocks. When I was teaching beginner painting, I found that rocks were a totally friendly medium to use. They were free and thus people were not intimidated if they made a mistake. Of course with paint, mistakes are simply painted over...no sweat. Teaching rock painting gave my students confidence in their new skills and gave them the courage to try more conventional works of art like painting on canvass.
When my students, had enough experience, they got to tackle a cat rock with all that lovely fur.
We used the Patio Paint brand paints that do not fade as quickly, if at all when put outside. It is important to note that before painting the rocks, they should be base coated with a spray primer called Kiltz. Now in Canada, we can no longer get that product, so currently I use Zinsser brand for all of my priming. It's a really sticky primer so that your project shouldn't peel. Of course the rocks have to be washed and completely dried before painting.
There are now other rock painting books besides Lin's. They all have their purpose. I still love her books the best, she's an awesome teacher and author. And no.....I have never met the lady.