redmeanie gives some good advice.
Also…some people may disagree strongly with this, but I believe in sniping (making a bid right before the auction closes). My approach is that I figure out what the item is worth to me (what kind of deal/savings I’m looking for), subtract the shipping cost and the remainder is what I will bid - at the last possible minute.
Why, you may ask, don’t I just go ahead and make that bid earlier? Because many of the people on eBay are idiots. They bid on items because other people have bid on them. I bid on a flat weight bench and some dumbass outbids me even though there was another identical bench being sold by the same seller (Jesup Gym - I highly recommend them) that had no bids on it and finished 10 minutes later. I went ahead and bid on the second one, winning it at the minimum price. And, because I couldn’t resist, sent an email to the guy who outbid me explaining that we both could have gotten the same minimum price if he hadn’t been so stupid.
Yeah, sometimes it can be a real burden - being so intelligent and surrounded by a world full of idiots. But the few of us that bear this burden must do so for the future of the human race.