1) Less is usually more.
Of course there are exceptions to this rule, but it's usually best to keep things simple. It's incredibly important for web visitors to be able to easily find what they're looking for and not be too overwhelmed by all the "bells and whistles" on a website.

2) Consider your audience.
Think about what your audience would like to see on your website, and anticipate their needs. For instance, a site for children would definitely need to incorporate LOTS of pictures so that they can easily find their way around the site.

3) Make the words on the page matter.
Most web visitors want information broken down into easy to understand verbage that is quick to read and understand. Of course, there is always a place on the internet for longer articles, but most text should be short and sweet.

4) Design for consistency.
A company indentity is vital for being recognized by web visitors. Having a website that blends well with any current printed materials (business cards, logos, etc.) makes all the difference when the public is called upon to remember who you are.

5) First impressions are everything.
You never get a second chance to make a first impression. Make sure that your website conveys the look and feel that best represents your business or organization.