In general, a webpage ought to be:
- Asthetically pleasing
- compatible with multiple browsers
- quick loading
- easy to navigate
- possessing a universal or root menu on all pages
You'll also need to determine what general layout your website will take. Will it be a linear "Slideshow" type design where users are intended to view pages in a particular order? Or will there be no particular page order?
You should consider carefully the color scheme for your site. Avoid harsh colors like red, orange and yellow for text and/or background. Make sure that your text color is in good contrast with your background (light blue on purple= bad; light blue on black=ok).
is a good (bad?) example of what not to do. Not only do they make your site look amateurish and cheesy, they slow down loading times for users.
Unless you absolutely have to, do not use frames. Almost every effect that can be provided by using frames can be duplicated by using tables. Frames and nuclear weapons are very similar: useful in certain situations, but should be used very sparingly!
Ensure that your HTML, XHTML, XML or whatever language you use is correct and debugged before launching. You can use the W3C's free validator to check most web-based languages (http://validator.w3.org/
Use good META tags to help search engines catalogue your site (Advanced Meta Tag Generator
Provide a method for users to quickly and easily contact you, at the very least you should include your e-mail near the bottom of each page with the copyright notice.
Hope this helps a bit!