I saw my first hummingbird this morning, so it is officially spring in Boulder, Colorado. Two things I do when if officially becomes spring - put up and fill the hummingbird feeders and clean all the contacts and connections in my stereo systems.
I use some very sophisticated tools to clean my contacts and terminations - one clean white cotton cloth, a microfiber cloth, and a bottle isopropyl alcohol. The routine is simple. I disconnect one end of the cable or interconnect and wipe thoroughly with the white cotton cloth. Next I check to see if there's any dirt or dark smudges on the cloth. If it shows signs of dirt, wipe with the microfiber cloth using medium force, then wipe down again with a clean section of the white cloth. If it comes away clean I'm done and onto the next connector. If it's still dirty I resort to a bit of isopropyl alcohol on another clean white cotton cloth and rub the part thoroughly, then dry with a, you guessed it, clean white cotton cloth.
It will be clean now, unless it's got oxidation or some form of goo (a technical term) on it. For this level of corrosion I resort to either replacing the cable (if it's short or cheap) or using Noxon to remove any oxidation. If that doesn't work my last resort is a very fine grade sandpaper to gently abrade off the offending particles. This must be done VERY carefully since it's all too easy to remove the sometimes microscopically thin layer of plating. This is a LAST resort. Don't say you weren't warned.
If you want to go that extra mile, you can use silver cleaner or a silver cleaning cloth (which is a cloth impregnated with jeweler's rouge) to polish terminations. AudioQuest even includes a small cloth with some of their cables.
And while you're in cleaning mode don't forget to give the rest of the cable a quick wipe-down. Also while your looking at your cables maybe it's time to re-route them all to keep the low-level signal cables away from your AC power cables. I know that properly dressing cables isn't exactly glamorous, but for the time and effort involved it's well worth your time, regardless of your hourly wages...