^^^ Step 3 on that wiki page is very important... Research your market .You have to look at the baseball card category (or whatever) and watch the auctions as they end. See how many end with no bids at all. See how many end with really low prices. Study the category carefully.Oh, and watch out for scammers. Good luck!
No it s not hard and it get s easier as start to sell things more often and build trust with the eBay community. You need to have a PayPal account probably. I ll just let this page go into detail for you.http://www.wikihow.com/Sell-on-eBay
HIYou should be open an account in any payment gateway. Then you can easily sell your product and if you want to buy some thing to online than you can use http://www.bid66.com.