I don't, they are stupid. You're hedging your bets on the promise that the "developer will deliver". Sure there's time to cancel it but either way the very concept of preordering is pretty dumb. You're basically paying for a game from which you have no idea if it will be good or bad (things can look good and still be bad), just to get it early and maybe to get some extra gimmicks that are worthless. Once you realize the game is bad, there's no point, the developers already have your money, even if you returned you'd get less that what you paid for.
Why lose some at all? Avoid the pre-order, then see if the game is good or not and then decide on that. What do you lose really? Not having it early, some gimmick that will turn up to be useless in the end? Pre-orders are a waste of money, the very idea behind is ridiculous.
I don't typically preorder either, but it depends on whether or not one considers the additions (if any) to be worthless.
If it's a game that I definitely want to get early (which doesn't come around too often) and expect to buy Day One, and there's an incentive that I care about, then I'll preorder.
Obviously part of that thought process involves my history with the game company and the level of trust I have with them. Same with things like Kickstarters.