I have to say, I'm not a very good negotiator, and the thought of haggling makes me squirm. Coupons and discounts, yes; insisting on prices when they don't come up on the register, sure. But brazenly marching up to a salesperson and demanding a discount just because?
Well, if you're brassier than me and you want to know how, check out this Consumerist post with a link to a Washington Post article. It may just change your mind on begging for deals.