Welcome to the board.
What makes a tack driver?
The single most important factor in determining accuracy is the nut squeezing the trigger. I've shooting competitively for about five years now. Plenty of times I've seen rich guys dump thousands of dollars into their equipment, only to get their butts whupped by guys with stock barrels, minimal modifications, and modest spotting scopes.
So, my advice is to get some quality ammo and go shoot! Once you feel comfortable with your new toy, THEN start talking about modifications.
EDITED TO ADD:
OK. OK. As far as modifications go, the first thing I would consider is the trigger. Is it good? (If it's still stock, the answer is probably no.) Consider having it worked on or replaced.
Everything after that depends on what you want to do with the rifle.
Speaking of which, what DO you want to do with it?