For ponies, use acrylic paints. If you don't want to spend a lot, you can start with inexpensive brands that come in bottles, at walmart, michaels, or other craft stores. You can get them around a dollar a bottle. Better paints will do better in general, but I use the cheap stuff and usually have no issues. It's also better to water them down a bit, they go on smoother, with less brush strokes. Lots of light layers instead of a few thick ones. To help prevent sticky-ness and chipping, you also want to look for a good sealer, like watered-down modge podge or testor's dullcoat.