Purchase an at-home sizing kit for each shape and length.
 
Not only do we each have nail beds of varying widths, but varying lengths as well. Someone who may want an extra-short almond set may not have a nail bed short enough to accommodate this, without their own nail poking out at the top corners. Purchasing a sizing kit is the best way to make sure your handmade press-ons are an accurate fit.
 
Each kit comes with one nail per size that you can remove and fit to your own nail. Write down the corresponding size per fingernail in the brackets shown, making sure to do each finger on each hand.