1) Quality of content: Search engines are actually pretty smart. They tend to pop up the best content, so the best way to climb on top is making something worthwhile for the sites audience. So matching your sites content against what people are looking for seems like a smart idea. Use Google Insight tools to dig into the existing consumer behaviors to match your content with what people are searching for. Let's say you have a site about Ice-Cream. What should the content on your site be? Looking at the most common related queries would be a good place to start.
2) Frequency of updates: If you want to top the charts in Google, you need to look alive. Search engines hate static pages that seem to be frozen in time, so it might be a good idea to create an editorial calendar that spreads out the content over time. It also makes managing your site easier as you don't need to create everything at once. This is the reason why corporate blogs are a good idea, as they are a natural way to keep publishing new content. Editorial calendars also make planning messaging across multiple channels easier - anywhere from tv-campaigns to tweets.
3) Inbound links: This is the vaguest one of them all, as it is hard to test. But urban legend tells that Google in particular is sensitive to inbound links and that they affect search rank significantly. I think it is just good practice to first of all cross link your existing web properties and then encourage track backs and social sharing. It doesn't hurt to add a "Tweet this", +1 or a LIKE button either, as they could push more links and traffic in too and generate inbound links.
4) Don't sabotage yourself: Yes, there are some best practices in creating content, but if you avoid the big no-no's, like big-ass Flash elements that don't have HTML equivalents or not adding alt tags to images, you should be fine. Choosing a good CMS should make making content search engine friendly pretty easy.
And that's it. You're now indoctrinated into the dark circle. Robes on the left, candles and knives on the right.