Here are a few tips you can use to keep your chain saw sharp and cutting efficiently.
Use a jig to hold the file(s). It not only provides a better grip for your hands, its parallel lines provide more visual cues to keep the file at the proper angle. The Husquavarna file jig pictured holds two files, one round to sharpen the teeth and a flat file that simultaneously lowers the profile of the rakes. (Photo 3).
I use a second jig in conjunction with the file jig to make sure I maintain the correct sharpening angle by keeping lines on both jigs parallel. (Photo 4).
Devise a method to hold the saw firmly imobilize so you can use both hands on the file for greater precision. I use a wooden clamp and a bench vise, as shown in photos 6 and 7.
Keep things light - don't use heavy pressure on the file. The lighter the filing pressure the more precise control you will have.
Count file strokes and give every tooth the same number of strokes using the same pressure. This will help keep chain wear even and and your cuts straight. If the teeth on one side become more worn down than the other, give them two less strokes for several sharpenings to even things out.
Go around the teeth on both sides twice
The second sharpening goes very quickly and the finer edge makes cutting faster.
Sharpening each tooth twice gives an "average" of all the strokes and helps even out inconsistencies in your technique. Light pressure on the second pass gives more accuracy and a sharper edge for smoother, cleaner cutting.
Don't try to sharpen every tooth perfectly. Give damaged teeth the same treatment as others - extra filing to eliminate damage lowers the profile of a tooth and it won't cut much anyway. Repair the damage over several filings.
Don't postpone sharpening until the chain is "dull". Lighter, more frequent sharpenings are quicker and keep your saw working at peak efficiency.
Avoid cutting rotten wood. Wood is earth transformed, and when it rots away it turns back to earth. Earth, stones, and rotten wood are natural enemies of sharp chain saws. Rotten eggs are ok.