Communication is key to ebay. If both parties follow the standard rules then both parties will incur a smooth transaction. There should be prompt communication from both parties. This might involve the seller answering questions about their items.
The seller should send an invoice quickly and the buyer should respond quickly aswell. If either party knows that they will be indisposed at the end of the auction this should be pre-warned. It is always better to let someone know that you will not be available, rather than for them to keep sending mails that may be unanswered.
If a dispute arises from a transaction, this should be dealt with politely and amicably to avoid conflict. If a resolution cannot be made then it should be referred to the Dispute Console of ebay BEFORE leaving any feedback.
Remember you have upto 60/90 days to resolve any issues. Paying via paypal is advised, as this sometimes comes with insurance.
Happy Bidding/Selling to you all.