There are ways, though explaining them all to you would take a rather long time. Just stick with standard xHTML and CSS. Try to avoid doing stuff that is too fancy. At first i was like you too, firefox would look fine then IE would look like someone just bombed the website.

After sometime you will get the experience and find out how to make both look the same with just one CSS file. To do fancy stuff however you will normally need to use work-arounds (aka Hacks) which will only affect a particular browser.

Google around for "CSS compatibility hacks"

and mind explaining how that is going to help?