Generally speaking, the worse a product is for your hair, the better it is for your synthetic wig. Cheap hair sprays (Aquanet) work great on wigs. There's a gel...Ice Spiker, I think?...that's been recommended too. Holding the wig upside down or holding the hair up while the product dries helps the anti-gravity effect. ^_^
The best way to keep your bangs up is spray them down with a cheep hairspray and take a blowdryer on low heat over them in the shape you want, it will hold the shape alot better. Light heat is all you need to style a wig. If it gets too hot for your fingers its too hot for your wig. Dont want to melt it!