The vinegar solution (or just full-strength white vinegar) and a soft toothbrush would work. Be careful to rinse it fully with water afterwards and then with isopropyl alcohol to dry it out (because some of the vinegar may creep into the wiring pigtail. The emery board may scrape up the contacts too much making it more likely to corrode again later.
Deoxit which is available at Guitar Center is purpose made for this. Also a battery terminal brush will clean up sockets for 1157 and similar bulbs nicely. Protect with a smear of silicone grease like Sil-Glyde.
Depending on how corroded it is and where is it emery paper for the socket and pink eraser for the contacts and then use light bulb grease on the bulb sides and contacts to protect from more corrosion.
fine sandpaper will work, but there is usually more than rust there, old grease, dust, dirt, problem with sanding it, it will work great, right after, but later it will give you issues again, when contacts rusts, the rust eats metal, and makes it thinner, and not as flexible\ springy anymore, sometimes tabs just break off during cleaning, we usually replace sockets, they aren't expensive, for older models, a brand "help" makes replacement sockets. wire clip splicers make the whole procedure a 30 sec thing. for more recent cars, you need to see a dealer, but i have not seem many newer cars that needed sockets cleaned\replaced, mostly after collision.
You have to be especially careful replacing sockets on older vehicles, because in a lot of cases many different sockets will physically fit the lamp's hole correctly, but only a socket with the correct focal length will allow the lamp to work properly/safely/effectively. Focal length in this context refers to how far into the lamp the bulb protrudes. There used to be many different focal lengths of a variety of fitting types (push-in, twist-lock, etc) but most of them have been discontinued for the older applications. That makes it easy to fall for a picture and mistakenly think "Yup, it fits right in, so we're good to go".
I use phosphoric acid metal prep fro the hardware store . Some lime and scale cleaners still have phosphoric acid but don't use the ones that have other acids. rinse well with distilled water or alcohol afterward. When dry use silicone dielectric grease or spray to avoid future corrosion.
I have salvaged many vintege lights this way. A few bad cases I have used a dremel w a little wire brush or a fiber wheel. and a little 90 degree pick to get the holding slots good and clean.
PS make sure you move the insert and spring so they are good and free to keep pressure on the bulb contact(s)
I see this old thread is back from the dead. Another thing to keep in mind, which came in handy with an antique flashlight recently, is that Barkeeper's Friend contains oxalic acid which is great for cleaning up copper... like the bottoms of Revere Ware cookware, or the copper contacts of a flashlight. If your light socket has copper contacts this is also an option, although I would flush thoroughly with something else after. Which reminds me, I need to try this on the lighter socket of the Jeep so I can charge my cell phone...