Do you specify a valid doctype? You can get Internet Explorer to be a bit more compliant by switching it into standards mode. http://msdn.microsoft.com/en-us/library/bb250395.aspx#cssenhancements_topic2
Do you use a browser reset CSS file? That can help bring the versions together. http://meyerweb.com/eric/tools/css/reset/
Be aware of IE’s CSS bugs: http://www.positioniseverything.net/explorer.html
For the skeleton of your layout, consider using markup that is known to work, such as http://matthewjamestaylor.com/blog/perfect-multi-column-liquid-layouts or http://960.gs/ for liquid or fixed layouts, respectively.
Keep up with JavaScript differences between browsers. jQuery handles some of them, but not all of them. http://www.impressivewebs.com/7-javascript-differences-between-firefox-ie/
Yeah, IE is a pain. If you want it to work in IE, you really want to test in IE every couple days. You don’t want to save the pain for the end–you want to handle the nightmares one at a time.
By the way, if you think IE is a pain, try looking at your page with a mobile phone. The other day I went to REI.com with an iPhone and the middle fifth or more of the screen was taken up by a bunch of garbled markup that rendered as text.