Have a good product.
You could have a great ad position, great landing page copy, and the best conversion rate in all the land, but it won't matter unless you have a great product.
It's something I've known for a long time, but now Joel Spolsky is unknowingly backing me up in his latest column for Inc. Magazine. Spolsky wrote about the first few years of his company, Fog Creek Software and how they made very little money because their business model was out of focus. They were busy making (or trying to make) distribution deals and an affiliate program. But the company took off when they made their software better.
When you focus on making a product better (i.e. filling a consumer need), people take notice.
I was watching Shaq Vs. last night. It's a program about NBA superstar Shaquille O'Neal challenging other sports stars to their own sports. Last night's episode featured Olympic gold medalists Misty May-Treanor and Kerri Walsh. At last year's Olympics, viewers noticed a strange taping on Walsh's shoulder. It turned out that Walsh was wearing Kinesio tape to help support her shoulder after undergoing surgery for a torn rotator cuff.
KinesioTaping.com went from 600-700 visitors a day to 345,000 per day, according to the New York Times. Yes, the Times gave them a much-coveted backlink and you can bet your bottom dollar that wasn't the only one they got as a result of the coverage.
The goal of SEO isn't SEO. The goal of SEO is sales. You'll get a heck of a lot more sales when you've got a solid product.