My suggestion is do not try to take the trigger apart. It's something of a pain in the butt to get back together again.
The best trigger group I've ever come across is from a place in Detroit, called, I believe, DC Guns or DC Engineering.
I did an article for American Rifleman on legal modifications to the SKS back in 1994, and they sent me a "competition" trigger group.
It was, to put it mildly, incredible.