After struggling a lot with the browser specific hacks to target IE/Webkit/Whatever, I have now switched to CSS browser selector [1] and never looked back. It simply saves a lot of time and effort. If you think about it, the User Agent String is the only accurate information that can be used to sniff the browser name and version, not some random CSS hack.

BTW the article is mostly useless for any practical use. If you really want to target IE6/IE7, this article [2] is a nice start. Learn about what types of bugs IE support and try to remember the name of the bug so that you can google a fix for it when you actually encounter one. As others suggested here, try to understand at least the basics of box model and how it is different in IE, but don't try to get a PhD in any IE bug you encounter. Fix it as fast as you can using whatever easy way out you can see an move on. There are better things to do in life.

[1] https://github.com/rafaelp/css_browser_selector/

[2] http://www.virtuosimedia.com/dev/css/ultimate-ie6-cheatsheet...