A tiny little trick I use to keep track of my cast on stitches because there's nothing worse than being short of a few stitches at the end of the first row of knitting. If you've miscounted a hat cast on, or a sleeve cuff that's only mildly annoying and can be quickly redone. But what about a 100 stitches of a top down collar or a couple of hundred of a bottom up body circumference? How about 300 or 400 on a shawl that's knitted from the edge up?
Get ahold of a bunch of stitch markers before you begin on your cast on and place them at equal intervals as you go. The number of stitches in between the markers has to be the same every time but you can place them at whatever distance you prefer – 10, 20, even 50. Once you're finished, all there's left to do is count the markers and multiply them by the number of stitches in between then add the final lot of stitches left after the last marker. Remove markers on the first row.