For smaller individual wires, 16GA to 10GA, I also use the IDEAL #44-103 1 - 45 number kit. These are a cloth tape numbering system that only require one piece of "tape" rather than making your own double digit numbers with a 1- 9 numeric kit. They are also available in higher numbers if you need them.
I buy the IDEAL #44-103 at Home Depot. They are quite inexpensive and a single book will last you multiple wiring jobs.