I use conditioner (hair or fabric) and style as any other gen pony
Soak in conditioner for a while - anything up to 24 hours if hair is really frizzy, then rinse and style. You can wrap around a leg for a classic pony flick, around straws for ringlets or use a straightening iron to get rid of frizz (make sure the hair is doused in conditioner whilst using the iron, as the tinsel will melt. I have done G3 tinsel hair this way with no issues)