Here is a clever little how-to: a hair turban from a hand towel! I learned this trick from a hair stylist back when my hair was half-way down my back, and I was so impressed that she was able to get all of my hair up in a little towel like this! This is better for wet hair because it keeps it from being broken or damaged by twisting it up with a big towel.
First, take a hand towel, and fold it corner to corner. You will want it to look just like this picture: imagine it lying flat out, and fold it from the top left corner to the bottom right.
Flip your hair over, and then lay the long edge of the towel against your neck.
This is where you wrap the towel around your forehead. Fold the left side snugly against your hairline.
While still holding the left side tight, fold the right side over it. Tuck the corner of the right side into the pocket made by the fold on the left side of your head. You can see my left hand opening the little pocket in this picture.
Flip back the two little flaps, and wrap your hair into a little bun on top of your head. Stand up straight and keep the bun piled up on top there.
Now you'll fold those two little flaps over the bun. Start with the left side, and fold it over, then tuck it between the towel on the right and your hair.
Fold the right flap a little into itself, to make a thin little flap.
Take this little flap, and tuck it into the pocket on the left side of your head.
Now your head is all snuggly and warm, wrapped up tight! Sometimes, I wrap my hair up when I'm taking a shower and don't want to wash my hair, rather than using a shower cap.
It takes a little while to get the hang of this, but practice, practice, practice! It's worth it!