My Old Girlfriend

One hint: design your pages in accordance with the standards, testing initially with browsers that are highly standards compliant, like Firefox, Opera, and Safari. Then test with IE and make what minor tweaks may be necessary to overcome IE's defects.

This may sound counterintuitive, given IE's popularity, but it is easier to design pages properly, in accordance with the standards, and then to make minor tweaks to accommodate IE, than it is to design pages improperly, for IE, and then to figure out how to fix bad code to make it work with good browsers.

For a more thorough treatment of website testing, read this article from C.A.'s Browser News newsletter.

More thoughts, from The Alternative Browser Alliance.