First off, the definitions: Polishing the breech face. Consider the relative motion between the face and the base of the cartridge case. That is, the base slides up the face as the slide moves forward, right? So, there is less friction to inhibit proper feeding/seating.
Throating/polishing (the feed ramp of) the barrel. Reduces friction between the nose of the bullet and the feed ramp.
Ejection port work. Alleged to make ejection more reliable against stovepipes. Helps reduce dinging of brass on some guns.
Tune extractor. The rim of the case has to slide up and push the extractor slightly to the side. Careful polishing at the point of contact reduces friction.
Bevel mag well. Cutting an angle at the entrance to the mag well, and rounding and polishing the upper edge of the angle, greatly assists in speed reloading. Also achieved by extension-grips with built-on beveled section.
Crown barrel. It is important that the end of the barrel be cut 90 degrees to the axis of the barrel for best accuracy. Most match-type barrels already have had extra attention paid to this. If no dings from careless handling, standard barrels commonly are okay. Easily checked or performed via a lathe.
Other "goodies" which improve accuracy include a somewhat longer link-pin for a tighter lockup, and a fitted barrel bushing.
For a beginner with a limited budget, I would suggest a set of sights appropriate for the type of shooting you most generally will do, and a good trigger job. In my own opinion, a four-pound pull, with no fore-play or after-play, which breaks like a glass rod, and does not let the hammer "follow" when the slide goes forward is a Good Thing, and makes for better shootability than almost anything else.
If you are going to compete in IPSC or IDPA, the beveled mag well is also a Good Thing. I have it on a purely self-defense LW Commander...
Find a copy of Halleck's book on the 1911 and read through it a few times. It'll help you understand what is to be done, and the effects of the work...
FWIW, hope this helps.
Art
