There are LOTS of ways to do this. If you use non-slip on your clips, you put it on the top part of the clip so that when the clip is open, the bottom part easily slides into the child's hair. There is a tute using aquarium sealer here that has been popular: http://hipgirlclips.com/forums/cleve...ip-grip-5.html
If you scroll down to the 4th posting on this page by member jenndga, she has a tutorial on how to do it. Other people just line their clip with hot glue. I am still awaiting my hubby's next paycheck and then I am going to get member Wendy's tutorial that has OUTSTANDING reviews on it. You can find her tutorial for purchase here: Etsy :: punkynmunky :: How To Make A Silicone No Slip Grip For Hair Bows,Clips, and Headbands
I have read others that use shelf liner, but recently it seems more people have been less than thrilled with the results. HTH!!!