Make sure your auction is open for at least one weekend, as this is when most people use eBay.
Much of the bidding takes place in the last few hours or even minutes of auctions, so make sure it finishes at a prime time, such as lunchtime or in the evening. It will finish at whatever time of day you start it but you can set your auction to start at a specific time in the future for a 6p fee.
Adding extra photos and descriptions does cost more but can make your listing far more attractive. Watch out for eBay's penny days when you can add these features for only 1p.
Set your starting price as low as you can bear to to attract more buyers. Avoid reserves as they can be offputting to potential buyers.
If you're selling lots of items at once, try using eBay's turbo lister. This allows you to create listings in bulk so that you can upload them more quickly. You'll find the turbo lister through eBay's site map.
You can monitor items similar to those you're selling by clicking on eBay's 'watch this item' function. You'll receive an email when their auctions are about to end.