+10 You really have no idea what the other bidder bid. You only know they bid more than you.

Always, always, always, snipe your maximum. +1 and always an odd figure. Do not base your bid on what the bidding is currently at. Many people do not bid until the very end, so the current bidding level often has nothing in common with the final price. Base your bid on what the item is worth to you. If your maximum is $100, then snipe $103.79, or something similar. And if someone else then wins the item, so what, it was worth more to them than it was to you, even if that difference is just 9 cents.

+1000 Do not play games with bidding and then canceling bids. Someday, you may just want to sell something on ebay, its just bad karma. I really do not care what someone else is willing to bid for an item. That has absolutely nothing to do with what the item is worth to me. And a smart competing bidder will not bid until the final 5 to 10 seconds, so there is no time to figure it out anyway. On my last buy, I bid with six seconds left. That was my only bid on the item. And of course, my snipe program does it automatically, I do not sit there trying to time it for the exact last moment. I never bid during an auction until the last six seconds. There is no benefit to me disclosing my interest to other potential bidders, particularly those newb's that tend to raise their bids when they see other bidders. And if I had been beat out on that item, no problem, as it then went for more than it was worth to me.

Values on ebay are kind of wild. Some stuff goes way over market, some stuff goes under market.