If you are joining ebay for the first time, you need to do the following:
1. Sign up
2. Resist the temptation to start bidding/selling/buying etc.
3. Go straight to the "COMMUNITY" section (see picture)
4. Research this section until you get sick of it. Really. If everybody did this first step, it would reduce complications in the future.
5. When you are ready to start bidding on ebay, do the following - check the seller's feedback (click to enlarge)
If you are satisfied with their feedback score and comments, start bidding!!
It is a good idea to start small with your first purchase (I should take my own advice!!) just to see how it all works.
5 Things First Time Ebay Users Should Do