Directory Structure

There are three basic directory structures you can have, flat, deep or somewhere in between. A flat directory structure puts all of your site pages on the same directory level. Each page is essentially one click away from the home page and no page is given any type of prominence.
A deep directory structure is the near opposite. Only a few pages are accessible from the home page, then a few more are accessible from those, a few more from those and so on. This puts some pages many clicks away from the home page unnecessarily.
You want to be somewhere in between. You want a directory structure that makes sense. Pages should be grouped together in broad level categories and only sub-categorized as makes sense from the navigation standpoint. You can go a bit deeper with your URLs but again you don't want half a dozen directories
when a few will do just fine.