Having a clear, defined, numeric & qualitative (action-oriented) goals is the primary success factor for your SEO strategy. Make sure you know exactly what you’re looking to get out of your time and energy. Make sure that nothing is sacred. If you say “we’ll only change the live text, not the design in any way” then you’re limiting your ability to respond to the goals.
Make sure the creative, analytical, and detail-oriented perspectives are represented on your team, and that a visionary, passionate leader is in charge of decision-making. Be sure you do some analysis of where you and your competition are in the search engines before you start. And narrow your targets as tightly as possible. If 85% of your business is less profitable, then go for the 15% that’s highly profitable. Consider creating mini-sites for search engine specific needs.