Most website builders are set up so that if you follow their templates, you shouldn't make any serious web designing mistakes. Nonetheless, keep the following in mind:
If you are uploading any photos, make sure they are optimized for the web. If you don't know what that means, get someone to do it for you.
Please, please, don't add music to your page. I personally find it to be most often to be obnoxious without adding anything to the page. If you do add it, make it soft with some means of easily turning it off. The reality is that a lot people surf the web at work and don't welcome an audio announcements of their surfing.
Keep fonts consistent and easy to read. This is not the time to go off the beaten path for interesting fonts. It could cause problems in loading your page.
Buy your own domain name. They're aren't expensive and it looks professional on your business cards.
