Web freelancing and taxes (U.S.)

How do you guys handle paying your taxes for freelance work? Personally, I’d like to pay upfront and get a tax return rather than pay later. However, I was reading that a good way to operate is to calculate how much tax you might owe and set it aside ahead of time in an interest accruing account.

Anyone know any good guides out there (which forms to fill out, how to keep track, etc.) ?