MT has worked wonders on filling in my edges and the new hair is thicker and gaining a great deal of length. That is a major accomplishment since I ate my edges up with microbraids over the years. Castor oil helps also.Girl, I don't know, and I'm still working on it. My hairline is fine, fine, fine - baby hairs, almost, and since my locs, my hairline ain't been right. I'm still working on them though.
I try to use little to no 'pressure/stress/pulling' on the edges. If they are fuzzy, fine, I don't care - I'd rather than then pulled tight (and they look a little fuller fuzzy, too).
I give my edges extra moisture.
I'd about to start using a new MT mix on my edges, to see how that works out.
Believe me I have tight coilies all over my edges as well as some nappier non-coiled kinky hair. What I do is just let them be unless I am flatironing or something. If I airdry they stay how they are. Sometimes I put Fantasia IC gel or Let's Jam on them but they are fine during that.
If you mostly just leave them be they will be fine, don't put any shampoo on your edges either (especially since you wash your face and neck daily anyway). Extra conditioner needs to go there and for longer because they are usually dry. You should detangle with your fingers then a fine tooth comb just to avoid knots or matting which will call little hairs to snap off.
When I was relaxed my edges and nape grew because I relaxed them bone straight (those parts of my hair do not agree with texturizing) and did not flatiron them when I straightened my hair. They would be straight already so I left them be until they were long enough.