How do you clean tube pins?

I'm sure there must be some discussion on how to clean tube pins (both power and small input tubes), but I haven't been able to find much on the subject. Specifically:

1) As tube pins are so close to each other, what tool do you use to clean the pin?
2) What solvents do you use?
3) How often should you clean tube pins?
4) Any other advise / suggestions you'd like to share.

In advance, thanks for any suggestions you may offer.