Right, I have mad curly hair and spent years either straightening it or doing far to much with it, the trick is to let your hair do what it does naturally and not interfere to much.
This book
http://www.amazon.co.uk/Curly-Girl-Lorraine-Massey/dp/0761123008
is great, and this link should also be helpful
http://www.wikihow.com/Follow-the-Curly-Girl-Method-for-Curly-Hair
Simply, stop using shampoo - it strips the hair of all it needs to stay sleek and curly and makes it frizz. Wash your hair using a conditioner that is as natural as possible and doesn't have loads of chemicals in, esp any silcone - I'm using Faith In Nature lavender and geranium at the moment, Boots do a very basic one that's good as does the Aussie Hair company.
After washing, blot your hair dry, don't rub it or towel dry it, you need to keep the curls in and ringletty if possible. I then put some wella setting lotion in my hands ( not very much) and scrunch it in, then add some clear gel - at the moment using Alberta Balsom but Superdrug own brand is fine - again, not very much but scrunch it in to let the curls separate. Then, leave it. Don't dry it and try not to touch it. I've been doing this for about 12 months now and my hair has never looked better,and I have lots of very thin and frizzy hair
Photo below was what it looked like on a very windy day when I was on a boat, despite the conditions you can see how the curl was holding up.
I never brush my hair now and comb it maybe once a month to get the tangles out. It took about 3 weeks of doing this system before my hair looked how I wanted it but I wouldn't go back now
Photo below is (a very rubbish and blurry picture of )what it looks like now after me doing ^^ 12 hours ago -