You'll need: A simple hair tie, best are ties that are slightly darker than your hair or slightly darker than the color of the yarn (you won't see them shining through later). Yarn in a color you like. A crochet hook, mine was size 3. Scissors.
 Start with a slip knot and continue with 5-7 chain stitches. This is the first end of the "ribbon".
 Next, take the hair tie and place the crocheted chain on the front side and the rest of the yarn on the other side. With the hook grab the yarn and pull it through the hair tie and up, forming a loop. You should have two loops on your crochet hook now. Get yarn from over the tie and pull it through both loops. Again, pull yarn through the tie and up, forming a loop and pull yarn through both of them. Continue crocheting all the way around the hair tie.
 If you're done, finish with 8-12 chain stitches to form the second "ribbon" end.
 With the last stitch, cut the yarn and pull it through. Cut both ends of the yarn a bit below the first crochet stitch. Tie a knot with both ends. You're done!
For the other two, start immediately with crocheting around the hair tie. Try crocheting more rounds or different colors for different looks. And don't forget to hide the ends of the yarn!
I'm in love with the light and natural look of these hair ties. I might try more colors or different styles to fit every single outfit I have! If you try these, please send me a picture, I'd really like to see your designs!