If you're new to ebay, have never used it before and find it all a bit confusing or just simply can't be bothered with the hassle to research and list items you have Trading Assistants are a good way forward. Generally the idea is that they can take away the time and effort of listing things you want to sell, and using their experience / knowledge, should be able to get you the best price possible.
10 Things To Look Out For:-
1) Find a Trading Assistant near where you live. It's always better to meet face to face with who may be handling your valuables or family treasures.
2) Are they a business seller or private seller. It is probably best to use a business seller as they are likely to have more invested in it, with (possibly) less to hide and are more tightly governed by various acts such as Sales of Goods Act, Distance Selling Regulations. You don't really just want somebody who's doing it as a "hobby".
3) Can you go to them, or will they come to you. Some people don't like having strangers in their house. On the other hand, some people don't find it as easy to get out of their house, and would prefer somebody to come to them, or the item(s) might be too big to take on your own and you may need help.
4) What is their commission. Nobody does it for free of course. Make sure you know about ALL the fees up front, so you don't get any nasty surprises. This includes: paypal fees, ebay fees, listing fees, delivery fees (see 5), auction reserve fees, storage fees, cancellation fees.
5) Who pays for delivery. Some Assistants may make it less obvious, even put it in their small print, that you and not the buyer, will actually be paying for the delivery, and this will also come out of your final amount. This enables them to look good in the listings by offering "free delivery", although in the end, you're the one actually paying for it. (See point 4).
6) Do they use best offer/buy it now or auctions. If they are using auctions can a reserve be used. This is more expensive, but it may prevent the nasty surprise of your priceless Ming vase being sold for 99p instead of £99 ! Whilst nobody can guarantee you will get a certain price for something, you may have a minimum that you will accept.
7) Do they have secure premises if they are storing your items for you. Can you go and visit it to check on your items, or maybe you'll have changed your mind and will want to pick them up.
8) Check the feedback of the seller. You don't really want to be doing business with somebody with a terrible record who just doesn't care. Good customer service / the personal touch, is really the only way many small businesses doing the same thing can differentiate between each other.
9) What sort of things do they sell. If a person is only selling, for example, rare books, they may be less equipped or interested in getting the best price for your enormous bundle of designer baby clothes.
10) Are they easy to contact. Do they respond quickly to queries by email or phone and will you get updates of any selling activity. What is going to happen if you're item doesn't sell.