I always wait till the last minute and I think this is the best way. If you bid earlier and put your maximum amount, it may result in a pricewar with other bidders and at the end, you'll just have to pay a higher amount for the item. Just before the end of the item, try to evaluate how much you think you need to pay to win and for example, if you think that it will be won at a price around 50, you should put an amount like 51 or 51,50, just to make sure that you won't lose to someone who put 50 just a second before you do, and generally, most of the people are more likely to bid 50 than 51.