Just a short list of a few things that I was never told but learnt and though may be of some use. Most of all to make eBaying work for you if down to communication. Its just a few tips and may be of some help. If you have and more of disagree I'd like to hear from you. Thanks, Chris.
1 Not Leaving Feedback. Ok, there can be reasons for this like you've bought a present and you don't want it showing on your own feedback. I've done that. The problem is that most smooth purchases is; We buy and pay for something, we get it in the post, we're happy. But the seller don't know that we're happy until we tell them and the easiest way is to leave positive feedback then the seller knows that we got the item safely and can then return the compliment to us. Of course we may not be happy and wish to tell the world which brings me to..
2 Leaving Negative Feedback. Its always difficult to do though sometimes you feel you have to. All I can suggest is only do this as a last resort as we are all in the same boat and most disputes can be rectified easily at witch point the buyer can still leave positive and would expect the same in return. However expect negitive if you fail to pay or if you supply faulty goods and refuse a refund.
3 Overcharging P&P Fees. Sellers sometimes do this to circumvent paying fees. This is a huge no-no. We all like a bargain but if I buy a bargain then relise that I just got ripped off in postage costs then I would know that it wasn't so much of a bargain. I don't mind paying up to an extra 70p for packaging but any more than that and I feel done. Don't do it, be honest.
4 Not Knowing How To Search. Basically, not using the search variables to your advantage. You may be looking at auctions ending soon but there maybe better bargains just being listed so try searching under Buy-it-Now and Recently Listed. There maybe some right bargains that you're missing. Or why not try looking changing the location of the search. Have a good look at all the search options and see what ones or combinations could help you find what you're looking for.
5 Shop Internationally. This goes for buyers and sellers. Apart from once being sent a part refund on some records in US$'s (I'm in in the UK) which didn't bother me too much then I have never had a problem due to international location. Remember, international insurance is still only a pound or two so, not much more than the UK internal insurance so why not shop and sell worldwide.
6 Give Payment Options. "Paypal Only"? Why? If you're going to the post office then accept postal orders! If you have a Paypal account then you must have a bank account so accept cheques! What about cash? Not always advisable but a note sent recordered delivery is always an option.