Hello Modzy. The best thing I can tell you is to start with things laying around your house. I started by selling my old video games and movies. I took the money I made from that and visited the local thrift stores and bought item that I could make another small profit on by again selling them on ebay.
Too, try selling something that you have an interest in, as it will make the process fun and not a job. Plus by knowing your products, you will be able to provide good information to your customers.
I was able to start out slow, selling stuff around the house and build up my feedback, which in turn allowed me to develop good customer relations and service. I now have 2 ebay accounts and another account on a different auction site. Try to stay away from the risky products, such as electronics at first until you get yourself well established. I know it's very tempting to want to jump right in and make the big money, but you should try and learn the basics first, then move on up.
On ebay, use the tutorials as a good source of information on buying and selling. Also visit the 'completed listings' pages and take note on how the sucessful sellers are listing their items, subject titles, item descriptions, photos, etc..Remember if you want to be successful, copy success...gulfy13