As a newby to ebay make sure when wanting to bid that you check out the sellers percentage rate and see how many negatives & positived they have recieved.
Email the seller questions before bidding so you dont get stuck with a product if say insurance isnt provided and you want it toobe insured.
Make sure you add the purchase amount into the product you purchase so the seller doesnt have to wait for payment too long.
When looking at the product make sure you know whether its 'new with tags', 'new', 'second hand' and so on this ensures you know what you are really buying.
When purchasing a product i leave it till the last 5 minutes of buying time so the price isnt as high you can choose to do this or make your highest bid early. I find other people will try to out bid your highest bid quite often so you end up missing out.