It is actually very simple and if you have done some reading up on it, you are ready. A few pointers, don't put excess pressure on the file while you work using long even strokes and keep the file teeth as clean as you can. The larger the file, the better I find also. Years ago, my grandfather taught me to file with the advice that a file is a cutting tool, not an abrasive. I find draw filing relaxing and almost zen like. With a nice, sharp clean file, after you get the hang of it, a barrel can be completely draw filed, to a surface ready for finishing, in less than a half hour. You are not removing that much metal, just trying to remove the machine marks. After construction is complete and before finishing the metal, I always go back over the barrel lightly, there are always a few scratches and dings that need removed.