Some old shirts
Optional for wide headband: serger
Depending on your baby's age, or if they have a abnormally big/small head, you will want to adjust the length you cut your strips, but I think these measurements are fairly accurate.
0-3 months: 12"
3-6 months: 14"
6-12 months: 16"
The Narrow Headband
Turn your tube right side out. Iron the seam to the center of the back.
Make a cute little flower to put over the seam. I used my shabby rose tutorial.
Hot glue the flower over the seam. You're done!
Here's another variation on this same tutorial. I used my peony tutorial.
The Wide Headband
Fold your rectangle hot dog style with the right sides together. Sew along the long side of your rectangle.
Pull the strings tight until the fabric gathers into a nice little flower. Tie in place and secure with fray check. All done!