If I'm looking to keep the original finish on a set of hardware, I start with tarnish remover. I use both Brasso (found at the hardware store) and a homemade vinegar mix. The trick for me is to scrub it with an old, pink Snoopy toothbrush. :)
The vinegar mix is simple: mix 1 part vinegar, with 1 part salt and enough flour to make a paste. Brush on and leave overnight.
Brasso is quite harsh, so in a perfect world, I'd use the vinegar mix all the time. Time is the biggest determining factor for me. If I've thought ahead I use the vinegar mix, if I'm crunched for time, I reach for the Brasso.
This particular set was brass plated. More often than not, brass plated hardware chips and then tarnish remover isn't an option.
So I paint it.
Previously I used this method, but have since discovered Martha Stewart brass leafing liquid at Michael's. They sell another brand, but I can't find it online - but between the two there are plenty of shades to choose from.
I like that the leafing has more movement than the spray paint.
The best part - it covers in one coat.
Edit: Check out Wende's response in the comments for more useful information! Thanks, Wende!