If you like to wear head scarves but they tend to slip off your hair, I have two ideas for you.
The first is velcro: Cut a piece of Velcro about 3 inches long. You only need one side of the Velcro. You can use the "soft" or "hook" side of the Velcro. The hook side works better, but if you have thin hair it can poke into your scalp, so test it first by placing the Velcro under your scarf and wearing it for several minutes before you actually sew it on to the scarf. I like to attach the Velcro (on the scarf's hem) so it hits about where my temples are. Do not use "sticky-back" Velcro, instead use "sew-on" Velcro as it's not as stiff.
Second Idea: PS Clips or Combs: Simply sew 2 small clips on to the hem of the scarf. First fold the longest sides of the scarf in half so you know where the center-forehead area would be, then measure over 3 or 4 inches from each side of the fold and mark that measurement with a pin. This is where you'll want to hand sew the hair clip or tiny hair comb (along the hem line) The kind of clips that work best are the ones that open and close when you bend them back and forth. I myself prefer to use tiny hair combs that measure about one and a half inches across (If I can find them) because you can wear the hair combs along your temples or reverse the scarf and place them along the nape of you neck.
Bobby Pins will do in a pinch, but of you hand stitch several small clips or tiny combs on to your scarf then you'll not have to hunt for bobby pins again! I sewed clips on one scarf and 2 tiny hair combs on another and Velcro on a soft, wide head band. Each one works, it's all about what your prefer, but one thing's for sure, my slippery, chiffon scarves stay on much better now!
Directions to wear the scarves: first hook the combs or clips into your hair, then take about 6 inches of fabric from the top of your head and fold the scarf fabric forward over your forehead then backward again. This makes a "cuff" which covers the hair clips, combs or Velcro. If you can't see the clips, you'll not have to fold a "cuff", but if your scarf is made of a thin Chiffon or a slinky fabric, you probably will need this "cuff" to cover up the clips. No more slippage!