Am wholly indebted to Dave Chaffey's post at e-consultancy on what the factors that work most for SEO...

Here's the management summary:
On more general digital marketing training courses I still find it useful to refer attendees to the combined wisdom of the SEOmoz ranking factors checklist - although it could use a refresh since it's a couple of years old now.
This list is useful since it rates 30 plus ranking factors scored out of five in terms of importance by their panel of experts. The ones I highlight in training are:
On-page optimisation:
Title tag = 4.9/5
Keyword frequency and density = 3.7/5
Keyword in headings = H1 = 3.1, H2 = 2.8
Keyword in document name = 2.8
Meta name description = 2/5
Meta name keywords = 1/5
It's useful to highlight the myth of the importance of meta tag which so many generalist marketers seem to cling to...
Off-page optimisation:
Link anchor text contains keyword = 4.4/5
More backlinks (higher PageRank)= 4/5
Link Popularity within the Site's Internal Link Structure=4/5
Page assessed as a hub = 3.5/5
Page assessed as an authority = 3.5/5
Link velocity (rate at which changes) = 3.5/5