Sketching the eyes first always helps me get them more symmetrical. I also like to use the existing eye as much as possible (taping it off if the coat of paint is thin enough, for example).
DollyHair is my favorite place to get hair from. They have a lot of selection, but they can take around a week to get to me. I've not used hanks from there to do a fashion sized, so I'm not sure how much you need. Considering how much a normal G4 uses, I don't think you would need more than two hanks, but I'm sure someone experienced can give you a better answer.