Start buying copies of ImagineFX Magazine - sounds like you're trying to get better at more traditional painting skills (which is where the post-work will come in), and this is TONS of digital painting advice in both Painter and Photoshop.

Once you get some tuts for hair (yes, there are a lot out there, and this advice goes for women's hair), get a couple of magazines that showcase women's haircuts - yes that sounds bluntly obvious, but there's no better reference than real life shapes and colors. As for lighting, with practice you'll get better and better at it, and most of it will become obvious when you paint it even though your lighting is different than the photograph you're referencing.

At first your stuff is gonna suck - just expect it. It'll take more than a few times to get a flow you like, and then you'll start seeing your paintings come together - it's all about practice practice practice!

Good luck and have fun!
-Lew ;-)