I sold on Ebay from 2012 up until this past August when I closed up since I went away to University and couldn't take my inventory with me. But I also left because their policies have become very anti small seller and favors major sellers and corporations and Chinese seller and buyers. Small sellers have little to no protection from bad buyers that take advantage of them to get partial refunds/free items/etc. Their traffic has also gone down the toilet since a major hack back in January and a search that favors certain sellers items. Many sellers have left because of all this, and when the time comes when I start selling again, it will not be on ebay. I plan on moving to Ebid and Bonanza as well as some other places to sell my items and my two cents would be to go to one of these alternatives or another, sellers are better treated and their fees are MUCH lower (3-8% compared to ebay's 10-25%).
If you do want to sell on ebay, I highly recommend carefully reading the policies and rules so you know what you are doing. One mistake early on as a seller could end your career right there. Also know the fee structure of ebay AND paypal so you know how to price your items. I did enjoy good sales during my time as an ebay seller, it has put an extra $1800-$2100 in the bank from when I started to when I closed. 98% of them went flawlessly, but for the %2 where there was a problem of some sort, it was a massive headache and stress inducer for me.
If you do decide to sell on ebay, I hope it brings in the extra money you want. If you have any more questions feel free to ask or message me, with a 339 feedback rating, I think I could answer any of your questions.