From reading this forum, it seems like co-washing has helped to bring out and define curls for many members, so you might want to try that.
If your hair isn't already layered, you might want to get some layers put in. I know of several people who had very limp, frizzy and stretched out hair before putting layers in. After they got their layers done, their curls just sprung back to life, and they became really easy to style.
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