The best mod for shootability you can make on a 10/22 is ordering a match grade hammer and installing it....Brownells, about $30.
Get a Power Custom hammer if you have an aluminum trigger assembly, and a Volquartsen if you have a newer plastic trigger group.
Replace the firing pin and extractor with Volquartsen or Kidd pieces, and polish the bolt as described on sites like gulfcoastmasons.com
and tactical22.net. That's also cheap. The best mod for accuracy is to buy an aftermarket .920 barrel with a match chamber...it's a bit
of money but can get your groups under a half inch at 50 yards with good ammo. Trigger hammer, pin & extractor & bolt polish, and barrel.