Sure... well for painting hair I like to use a 3 layer approach. Start with a dark solid layer of paint over all of the hair... you might have to do two coats. Then dry brush on 2 progressively lighter shades. So for a medium brown I will start with a dark brown color, then two lighter shades of brown to give it a sense of depth.
As for the edges... one thing I'll do (especially on a beard) is after I paint the edge of the hair line, go back over it lightly with the flesh tone I'm using in order to get a subtle transition, if you look at how hair looks in real life it's not a clean break between skin and hair, there's a transition so you want to replicate this in 1/6.
As for the sculpting, it's kind of the same thing... you want to try and get a subtle transition between the two... and usually working the edges lower and tapering them off helps to acheive this. As I said before after I get the basic shape (but before baking) I'll use rubbing alcohol on a small paint brush to smooth out the sculpt and even help with that gradual transition into the skin... you'll understand what I'm talking abuot the first time you try it, the alcohol does a great job of smoothing out the sculpting materials.