Standard SEO caveat: It's a black box, and the algorithms are proprietary, and trying to predict and game the search engines is a crappy way to make a living.
That said, what are the baseline steps you want to take to make sure your content is visible to the major search engines (Google, Bing, etc.)
I'm specifically curious as to what role your URI Information Architecture plays. It's common wisdom that you want keywords in your URI, and you want to avoid the query-string laden approach, but what else beyond that?
A quick example of what I'm talking about. Based on something I read on a forum, I recently exposed a /category/* hierarchy on my site. In the following weeks I noticed a sharp uptick in my page views.
I'm curious what other basic steps a site/weblog should take with its URIs to ensure a baseline visibility.