I also would recommend a polymer varnish, I personally prefer Golden, but Liquitex works too. And because they’re acrylics you can water them down to do thinner coats to avoid heavy brushstrokes.
 
Also for metallics to get them to really shine it’s good to do the whole base in matte varnish and then go over the metallic spots in a gloss (and also eyes or anything else you want to accent.

EDIT: also liquitex or golden both have good silver paint, and the pearlex powder works too, but nothing beats the shine of using metallic foil

I bought a set at a target in LA, but I used sandbar to customize into my own character for my december desserts series. His body is more similar to a regular female body- he doesn't have the stallion broader shoulders/legs, but his head is the same shape as a stallion head, just smaller. It looks a little odd but I guess he's supposed to be a tween?