Browser based designing?

[eleven0]

Maybe this isn't supposed to be here but I have a question to ask.

I use both IE and Firefox.  I design sites. I'm not a professional designer but I can get around with HTML and bit of PHP.

I have been using firefox for sometime now. I realized that most of the site I designed looks weird in firefox. But it looks fine in IE. I just made a new template. I used firefox when I was creating it. Now, it looks fine in firefox, but looks weird in IE.

What i do is I add add some block in my template, then to check it, i run the template in firefox to make sure everything looks good. It looks good. But in IE, it's all messed up. It works the other way around too. It's like I gotta pick a browser to work with.

What can I do to prevent this?

[pkmnfrk]

A few tips:

- Use Standards Compliant HTML/XHTML (Make sure it validates)
- Use CSS (It has a validator too)
- Explicitly set padding, margins, etc, in the default block-level tags, and redefine them on a class-by-class basis (since, FF and IE have different default values for many thing)
- Same thing for font sizes and font families.

[eleven0]

Can you explain last two bit more?