This is something that is hard to learn from reading about, but by watching, you can. There are a few videos by AGI on stoning triggers, etc, on different firearms, and that is what I would suggest. Also, there is another video done by Jerry Miculek, who does this on S&W revolvers for speed target shooting, and is titled; "Trigger Job: Complete Action Tuning for Smith and Wesson Revolvers with Jerry Miculek". Have look at the videos by Bob Dunlap, on stoning sears, and the difference between negative, neutral, and positive sear engagement, before you start, so you will be safe.
Trigger Job Video: