1. There is more than one browser
Internet Explorer for windows is by far not the only browser around. You should test your website on both the Macintosh and on the PC. You can use Internet Explorer 6, Mozilla Firefox and Opera on the PC and Safari and Firefox on the Macintosh. Internet Explorer for the mac is no longer supported by Microsoft so don't bother testing, things will hardly work anyway with today's CSS coding.

2. CSS is the way to go
There is no doubt about it. If you are serious about developing websites you should use Cascading Style Sheets for both your layout and your design. This way you have total control over how your page behaves in all browsers.

It also adds great flexibility to your website for later on, when you are planning to do a redesign for example.

3. Create all your code yourself
Don't even try to use the Design view from Dreamweaver or Frontpage.

The code it generates is by far not what you want if you need to have full control of your page. For maximum control you should always work in the code view and create things yourself.

4. Use Mozilla Firefox for JavaScript debugging
The error messages Internet Explorer generates are quite irritating to say the least. It doesn't even tell you what is actually missing and on what place things go wrong.

If there's one browsers that can help you with your JavaScript development then Firefox is the one. The JavaScript console is by far the most detailed one and will help you very much when you are testing your scripts.

5. Use the Web development Toolbar for both Internet Explorer and Firefox
These toolbars will help you a lot because there are filled with debugging tools and handy shortlinks to useful tools.

The one for Firefox can be found at: http://chrispederick.com/work/webdeveloper/

And the one for Internet Explorer can be found at: http://www.microsoft.com/downloads/details.aspx?FamilyID=e59c3964-672d-4511-bb3e-2d5e1db91038&displaylang=en

You really need to have at least these toolbars!
So now you know what you need to have to be a successful web designer. Don't forget to download at least the toolbars. They will help you a lot and will save you a lot of time.