How do you clean tube pins?

Bend a pipe cleaner 180* dip it in Kontak cleaner and you will be able to clean all sides of a tube pin.

http://store.acousticsounds.com/browse_detail.cfm?Title_ID=13180

good listening....

Good info above but the tough question is how do you clean the tube sockets?

Any slight corrosion should get rubbed off the contacts when the tube is inserted, most are nickeled anyway. The ProGold or SST on the tube pin actually then somewhat seals(capillary action) the contact point, inhibiting oxidation. I've used small dental brushes(the kind that look like extremely small pipe cleaners for between the teeth) on tube sockets(of older equipment) in the past, with non-residue contact cleaner, to remove accumulated dirt.

Donaudio, pipe cleaners especially with Audio Top cleaner.

usually inserting and taking the tube out a few times should be all it takes as far as maintenance cleaning.
I usually use DeOxit for initial cleaning if I get a NOS tube set. Just make sure you use tiny bit. This stuff dries out fast and works pretty good.