How make looser waves without heat?

My hair is naturally curly and i wanted to make it loose and wavy without heat. I sometimes put it in braids but it just gets frizzy and curls. When i put it in a ballerina bun overnight and when I took the hair tie out, it just stayed in the bun all by itself. When I separated it, it was tight curls that were ugly. What can I do to make it wavy but not as curly without heat?