Is this a ’55 or ’56? You gotta know what it is before you can sell it!
Selling baseball cards is especially difficult if you don’t understand exactly what cards you have for sale! Learning to identify the various Topps, Donruss, Fleer, Upper Deck, Bowman, Goudey, Stadium Club, or Allen & Ginter can be absolutely overwhelming for a person new to the hobby. If you are fortunate enough to have some of the tobacco cards from the late 1800s and early 1900s it can be even more difficult. Then there are postcards, felts, pennants, die-cut cards and other oddball issues that seem to defy classification. Most price guides are limited on pictures so expert help is needed.
There are numerous excellent baseball card forums and baseball card chat rooms online that will welcome a new collector and if you post serious, sincere questions there are normally many people willing to help. The forum at Beckett or the PSA vintage sportscard forum may provide quick answers to your questions. If you can provide a scan, it is almost guaranteed that one of these advanced collectors has seen it.
Many of these same forums offer free Buy/Sell/Trade postings as well. By becoming a member, this may be another outlet to sell your less valuable cards without worrying about eBay fees or consignment commissions.