You would need to register as a business seller (When you start selling regularly, Ebay will "advise" you to do this as if your selling over a certain amount you will benefit from being a business seller), you will pay to list each and every item (unless you have a featured shop which costs £50pm and allows you to list 1200 item per month free of charge, or a Basic shop which lets you list 200pm), you will then pay between 5-11% of the value of the item (As well as a 5-11% charge on the postage cost that you charge) and you will also pay paypal 3.5% of the total to receive payments so factor that in to your sales price. Ebay fees can be found here for the various categories:-
Business sellers
http://pages.ebay.co.uk/help/sell/businessfees.htmlPrivate sellers
http://pages.ebay.co.uk/help/sell/fees.htmlI have feedback of 33,000 across several accounts and have encountered most of the types of fraud on Ebay such as:- Non receipt claims, Item damaged claims (Using a picture of a damaged item to claim the one you sent was damaged and get a refund), chargeback claims (they contact their credit card company to claim it was not them who made this transaction), address change claims (They pay with one address then email you asking for you to send to another address, DO NOT do it as Ebay/Paypal will just give them their money back as you shipped to an address that was not in the transaction, the fact that the buyer asked this means nothing!, only post to address on Paypal payment)
What you also need to be aware of is the amount of fraud on ebay (People buy something pay for it and then when they receive it say they have not had it and paypal/Ebay will refund them if YOU cannot prove its been delivered), so if you are posting things always try to use registered mail (Recorded or special delivery for UK mail and either International signed for service or Airsure for overseas).
Having a Separate account for your business is a better idea as someone is bound to ruin your 100% feedback due to them having a bad day at work
Getting negative feedback on Ebay is par for the course at some point as some buyers just don't have a clue, buyer will buy an item and it is thw wrong item he needs (Even tho he bought the wrong item) some will leave negative feedback lol.
Make sure you are VERY clear about the item your selling (Good descriptions and excellent pictures) and make sure your VERY clear about how you will post items and when, buyers on ebay tend to expect items to arrive the next day unless your very clear on spelling out to them what to expect.
We operate a 1 day shipping policy, on Ebay this means we will ship within 1 working day for items paid upto 3pm, so a buyer buys at 2pm on a Monday we will ship it on Tuesday at the LATEST (usually ship on Monday), if someone buys at 4pm it will ship next working day, also make sure you state which postal service it being used and also state expected delivery times (1st class is 1-3 WORKING days, 2nd class is 2-5 days but can take upto 7 days!).
Other than the problems you get from the minority (2-3%) its a reasonable place to sell.