I know its a lot easier if you have a friend there to help you, but it is possible to do it on your own with a good level of success.
I know my friend started off with the braid when she begun styling her wig. She did it well and we moved onto the bangs. For those, we used Got2b(the styling "glue". Works wonders) and positioned the bangs of the wig to how Undertaker's are. We had to hold it in place for about a minute before it laid correctly on its own without us.
For getting the choppy layers, all I can say is do not cut horizontally. That does not work out well for layers on a wig(or really for almost any style). Take your time with it, and don't rush.
Also, it might be a good idea to make sure you treat the wig so it doesn't tangle and knot super easily. My friend had such an issue with hers, and eventually after treating it with a shampoo her mother purchased(the small bottle was about $15 so lucky for her that her mother owns a hair salon) decided it wasn't worth saving and turned it into a Riku(Kingdom Hearts) wig after cutting it.
It was a gorgeous wig for Undertaker while it lasted though.
Hope that helps, and sorry I can't help more.