You could do a lot with her white parts......putting on my thinking cap.
I'll have to dig around later when I get home to see if I can find pictures of my horse Sugar. One year we had her painted in stripes like a zebra (she was all white) for an event -- the funny thing was that for a week after people would be driving by our place and slam on the brakes when they saw her up in the field, thinking it was a real zebra. It was kind of fun to watch.
Look up "trail of painted ponies". There are some really crazy ones. My sister collects them and I have one in my room and the horse has boots all over it. Maybe you could get some ideas? There are quite a few of them.
Another thing: Does anyone think I should do like a 'test' try on her to make sure she doesnt have an allergic reaction to it, or something along them lines? And if so, where should I do the 'test' painting??
I like the idea of painting just the outlines of her white spots in bright colors, then add the sparkly hooves and maybe some color in her mane, she'll look adorable. Be sure to post pics of whatever you end up doing!
With the white she's got, you can have alot of fun! Definitely take lots of pics of your finished work! Are you going to incorporate different colored tack too? Perhaps some sparkly tinsel type stuff into her mane and tail...well not tinsel, but I can't think of the word right now! That would be tight!