I had the same issue with my hair line while transitioning and still have that issue now (been natural for a year and a half). Honestly, I don't know if my method will work for you since I just used a thick fabric headband when I was transitioning ( I didn't even want to deal with my edges), but here is what I do now that I am completely natural:
1. Conditioner (real, not a leave-in), apply it to damp hair. I have a bottle of Suave tropical coconut specifically for this purpose, it instantly smooths out the hair. Pat, then smooth onto edges. It's cone free so it won't build up and dry your hair out.
2. Gel or wax, smooth it over your edges. I use Kiss My Face gel from Whole Foods, which is cone free as well and protein free (I think). It is a creamy gel, so it smooths rather than squeeks on your hair.
The hold is great as well. If you want super hold and can handle proteins, Giovanni L.A. naturals is great (cone free also) and gives the hair shine. I also use the Giovanni Wicked Wax sometimes to smooth down my hair when it is damp/dry since it doesn't work on wet hair. I use after the conditioner has dried a bit so I usually do this a day or two after I do the gel method, if I have a few minutes to spare in the morning, or on the weekends. The wax keeps my edges down until I wash it out so I tend to use it a couple days before shampooing.
3. Next, I use my 'Scunci smooth and shine brush'. Without these other steps, this brush alone can smooth out my edges, but I use the other products to give a polished look: http://www.walgreens.com/store/produ...&id=prod378517
The one I have is more rectangular ( not the round brush) so it's easier to use on my edges. I use the back of the bristles to slide against my edges and the tips lightly touch my hair, but don't rake through. I do this to avoid hairline breakage since the brush can cause that if you rake it (bristle's down) over your hair.
4. I tie my edges down with a satin (faux satin you can get a Sally's, drugstore etc.) scarf for like 5 minutes and voila, they are smooth all day long. You can leave the scarf on for longer or do this at night and sleep with the scarf. Your edges will be nice and smooth in the morning. hth.