Posted By:
Anthony S.Matt,
A nice resource for learning the very basics of myriad vintage baseball card sets is www.oldcardboard.com. It probably covers somewhere in the neighborhood of 150 - 200 different vintage sets. It doesn't go into extensive detail, put it does provide pictures of representative cards from each set, the number of cards in each set, and a rough estimate of what you might expect to pay for a common card in VG condition in each set.
Once you locate a few sets that appeal to your eye and pocketbook, the fellows on here are fantastic about providing a much deeper description of the vagaries of those sets. At times it's a bit awe inspiring how much certain individuals on here know about the sets they collect.