Best is to drill tiny holes like 1/32" in the middle of the stick at the top and bottom of safe range, and a couple in between. If the hole gets dipped in oil it will remain filled when you pull out the stick. Careful, I broke a couple bits drilling mine, the dipstick is some pretty tough material.
Alternately, dip the stick, then carefully lay it on a napkin, fold the napkin over, then back and you'll see the wet area on the napkin. If you didn't mover the stick relative to the napkin, then you can see where it comes to on the stick.
I prefer the holes. The holes have to be small 1) to hold oil, and 2 to prevent compromising the stick (a 1/8 hole obviously could result in the tip of the stick remaining in the engine someday, and would not hold the oil).