I have a whole list. 
Patience and consistency. SEO is easy, but you have to constantly keep learning and trying new things. It often takes awhile to see results. Keep working and don't give up. As long as you create quality content and links that are relevant, eventually your hard work will pay off. Constantly learning is another key. Search engines change their algorithms over time, and your competitors are always changing, so you'll never be done. I like to set my homepage to an rss feed reader, where I've subscribed to about 10 blogs ranging from SEO to marketing to copywriting. That way new information is always the first thing I see, and I'm less likely to waste time on games or random browsing. Finally, having a network of people to help and encourage you can make the difference between giving up and sticking with it. You can learn from each other and provide sympathy and sometimes a little healthy competition.
