Awhile back I used to use John Freida "Dream Curls." It's a spray you can put on while your hair is damp. My hair was always straight on top and wavy/curly underneath, and this spray really worked to even out the texture and make every part of my hair curly and nice-looking.
Dream Curls® Curl Perfecting Spray from the John Frieda® Hair Care experts
I would say definitely go with layers, with your shortest layer being about 5-7 inches long. Your top layer will be more likely to curl, and you can get some volume too. At least, that's how my hair used to work.
Now, I have a pixie, which I also highly recommend. It's very easy to style and work with, and it's very healthy now! I'm extremely happy with it. Of course, it's not for everyone!
Good luck with the hair!