Oil softens the leather up a little bit, and it takes care of it. But you should not overdo it. Personally, I don't use anything, I just buy a really...
Look it up on google, then gather prices from Ebay and/or Amazon. Find the average of these prices, and that should be how much the baseball card is worth.
Not really; it could take a long time before you make a large sum of money investing in baseball cards. Instead, consider keeping it as a hobby, and using the...