There's a lot to website design. I have my own site, so I'll add a bit of detail.
-Members should have an easy time getting around - a nav bar of some sort should be on every page of the website.
-Content, content, content. You can have the prettiest design on the Internet, but if you don't have anything interesting, not many people will join.
-People first look at webpages in an F-pattern format. Use this to your advantage - a banner is useful.
-It's always better to omit something than give a dead link, or a 'under construction!' message.
-Make custom and meaningful error pages. Honestly, do you like it when you click on something, and you get a white page with just 'ERROR 404' at the top left in big, black, bold text?
-If you're writing articles, don't put it all in one big, huge, giant paragraph. Breaking it up gives peoples' eyes "rest spots", and they will more likely read the whole thing.