If this is something that will improve your business, allow you to start a business, or in some way will have a positive impact on what you want to accomplish, then trying to game the auction won't be effective. First and foremost set what you are willing to pay for it in your mind based on what value it will have for you short and long term.

If it is a revenue producer, then if nothing happened to improve it, how long will it take to get your money back.

If it has some other positive impact, then determine what that value is to you and the very highest possible level and then set a dead hard last price on it.

On Flippa, I typically wait to see where things are at the last few hours. If it's got value to me and the bids are in my range, then I jump in at the last hour and see where it goes from there. Flippa extends the auction automatically though, so there's no value in sniping.