I've found a piece of old sequin embellished elastic and instantly decided to use it for a headband. It was a quick easy deal, only about 10 mins. You'll also need regular elastic band, needle & thread, a hot glue gun or just glue and scissors. Here's how to do it:
Measure around your head and find out the length of the normal and the sequin elastic.
Cover the seams with bias binding or normal ribbon. I used my hot glue gun for that.