There was a similar question on this site several weeks ago. Along with the answers were a blue zillion ideas and experience stories. I think you'll find the posts very helpful. My only experience has been with ammonia. It is nasty stuff but providing you take all the surface oils, wax and other contaminants off the brass first you will find a really neat aged surface. I wouldn't polish the brass first as a little mottled look will put you closer to the desired look of an old surface. Most have variances over the entire surface.
Scarf a glass bowl from your wife kitchen cabinets large enough to contain the ammonia and suspended brass parts from a cover you make out of plywood or heavy cardboard. Suspend the parts over the liquid ammonia and let set for 12-24 hours. The bowl should be covered tightly to keep the fumes inside and the brass you are aging should not touch the liquid.
Your problems will be four fold: getting all the oils off the brass parts, explaining to your wife why you are rooting thru her cabinets, not breathing the ammonia fumes and patience. I have started over several times but you'll have to learn that on your own. Best of luck. And remember ammonia is a nasty product. Be careful. Regards, HIB