Wikis are very easy to edit, which means they often get edited by people inexperienced with web design. Here are some handy tips from a human interaction designer:
When people first arrive at a page, eg. through a search engine, they only spend 4 or 5 seconds to figure out if this is the page they wanted. They have no time to read a lot of text, so don't write too much on front pages or other index pages. Actual articles can get more text, though.
First things first
On any front page or index page, list the few things that are people are most likely to want in their own sections. Just like is done on the KernelNewbies front page. If you have more pages that is fine, just add them to their respective categories, or link them from a page that is dedicated to that subject.
Think like a reader
If you were reading this site, what changes would make it easier for you to read?
Now that you're here, why not edit the wiki to make those changes?