Anybody who can tune a trigger on a single action Colt's Mdl. P type revolver will understand the principles, but you wont get a 'hair trigger' even if you try 'cause then it wont last.
That said, anybody who can be careful with tools can pull one down, clean and lightly (LIGHTLY) stone the sliding surfaces and put some old Gunslick or, my favorite, anti seize compound, on the sear tip and hammer notch and reassemble will have done what most 'gunsmiths will charge you $50 or more for.