I had great success with my Dremel tool and a polishing wheel attachment for it. Using a little jeweler's polish, I gave all contact points on the trigger, hammer, sear, and pins a high polish (until I could see my reflection in them).
Most all the contact points are obvious, especially to a person with your experience, but make sure to also polish the hammer face. That'll ensure no friction is going on down there, thus no microscopic metal shavings being produced.
I topped off the polish job with a good soaking in white lithium grease (synthetic moly grease would also be a good candidate), and ended up with a light, crisp trigger. Going into the project I wanted to end up with a crisp trigger without changing the weight too much (I prefer stock trigger weights, and realize that "lightening" a trigger is only the process of pre-wearing the internals - read: "dangerous"), and I was very pleased with the results.
The same could be accomplished with a buffing wheel on a bench grinder, or a man who is extremely adept with stone types and their usage.
Oh, editted to add - If you use stones, be very careful. I once stoned my trigger group in one of my FALs, and I must've broken through the hardened metal on the surface of the hammer notches. The result was a full-auto FAL after only about 40 rounds, so I replaced the entire trigger group to safe. I thought I knew how to stone, but knowing how to really sharpen a knife and knowing how to stone polish are two different beasts.