Originally Posted by
capnjonny
When I find the puncture spot on a tube I take a sharpie and mark an x over the puncture after I clean and sand the area. Then when applying the patch I can center it effectively over the hole. Also, I like to clanp the tube lightly to the work bench on either side of the puncture so the affected spot stays right side up and doesn't move.
I use a silver sharpie for that (There's also gold ones) Also a mark on the tire where the stem is is good for indicating where the tire is on the wheel. (handy for finding why you flatted)