You can use product but with mine, I shower at night and I dry as much of it as a can with a towel and then bundle it up on the top of my head with a hairband and sleep like that and when I take it down the next morning it looks like I got a perm lol. But it also depends on your hair.
Definitely braids. The curlier you want it, the more separate, small braids you use. If you just want wavy then do like one big braid or two medium ones, depending on how thick or thin your hair is. (:
My grandma used to take small sections of her hair, roll them into little donut looking things and pin them with Bobby pins. I think she called it banana curls? Not sure if that was her name for them or what other people called them? Braids will make your hair wavy, not necessarily curly.
Braids will make waves...so when my hair is damp, I twist it in a bun and when I wake up take it out and lightly blow dry it while scrunching...it works for me. Other than that... The answers above are good answers...(sponge rollers) also... I have a thing called a hairdini.. it's a long thing made out of sponge and the middle of it is wire... It was made to use to put your hair on a french twist...anyway.. I love that thing...I spritz my hair, bend over and brush all my hair into a high ponytail then roll it all onto the hairdini and secure it into a bun... The next day I have big beautiful curls... :D hope this helps. :)