Quote Storme:
I'm a little confused as to what you need advice with, I think. Are you asking how to spike the hair on top once you've braided the back?

If so, I think that, as the spikes are pretty naturalistic and the wig is fairly puffy, you can probably get away with pretty minimal use of styling products. There's a good tutorial on spiking over here: http://cosplayisland.com/tutorials/wigs/spiking

Quote Storme:
I'd suggest styling it a bit before actually cutting; that way you can see precisely which areas will need to be cut. Also, most wig heads are a bit smaller than real heads, so you'll want to check the length of the fringe and sides when it's on you before you cut off too much length.

I'd start by braiding the back, I guess, and then - do you have the goggles? I'd put them on the wig at that point so you can tell how much hair you'll need to have sticking up through there vs at the front and sides.

After that it's pretty much a matter of fiddling with how the hair lies until you're happy with the basic way it sits, and then trimming it down bit by bit anywhere that looks too long.