Bid early and bid low.
The best way to get a bargain is to find the item you want while it is newly listed and bid low.
eg. Ipod Nano can begin at .99c or even .01c. If you bid, then enter your maximum bid as high as you are willing to go, it is amazing how often you get bargains as all other buyers are intimidated by bidding unsuccessfully on the item. Remember that you only pay the total of your actual bid not the maximum bid