There are hundreds, or even thousands (limited only by human imagination) of ways to get more traffic to eBay auctions, but since many of them require considerable time, money, or resources, I'm going to discuss a few that I believe almost anyone can do. These methods should really only be used for items worth £25 or more, because the time and/or money spent would only be justified on more expensive items.

1. Find message boards that are related to your product and post, with the link to the auction in your signature. If you are selling a MIB (Mint in Box) 1980's Barbie doll, post on 80's message boards and also Barbie and doll collector forums. Be sure to read the forum rules, and do NOT post about your auction. Just post helpful and friendly responses to popular threads that are started by someone else.
2. Always use the gallery image feature. You will get much, much more traffic to each auction if you include the gallery image. It is well worth the extra cost.
3. Use the buy-it-now feature whenever you feel it is practical. If you truly don't know the value of an item, you may not want to use it. But for an item that you are absolutely certain is worth a particular price, especially if it is rare and in high demand, buy-it-now has the ability to make a person jump on an auction. See, a lot of people will ONLY use the buy-it-now feature. People have grown tired of bid snipers and such, and they want to be able to just purchase that salt shaker that completes the set they have been trying to put together for the last five years, without worrying about being outbid. Sometimes, on especially nice items, people will pay far more for the guarantee of being the winning bidder than they would have otherwise. Unless you really have no idea what the value would be, buy-it-now is a very important feature.
4. Make use of the title to its fullest potential. So many people overlook this! If you put the title as only “1980 Barbie Doll”, you will miss a great deal of traffic from people searching for things like “80s Barbie”, “Pink N Pretty Barbie”, and “Barbie MIB”. You should try to get as much out of the title as possible by inserting as many descriptors as you can, but make the title attractive, at the same time. Try something like “MIB Pink N Pretty Barbie 1980 Rare 80s Doll BIN”. This gives you more bang for your search buck when people aren't searching descriptions, also. You can use up to 55 characters, but be aware that this includes spaces and punctuation. Use as little punctuation as possible to keep precious characters available for searchable terms.
5. Use enhanced listings whenever the price makes sense. If you are selling an item that is worth under £25, then paying an additional £2.50 for a highlighted auction is not going to make sense. And it certainly wouldn't make sense to pay £9.95 for Featured Plus! But paying 50p to bold a title is certainly worth it for most auctions that are over £12 or so, especially for items that have a lot of competition and are not “everyday” items like household products or standard clothing.

To conclude, I'd just like to remind you to use these tips whenever you are selling an item worth £25 or more. It can really be worth it to help get those extra visitors!