What strategies have you found to be most effective for increasing organic traffic in a competitive niche?

[Shortie]

Creating a website in a competitive niche is never easy due to the amount of competition that there is within that niche. One of the ways to ensure success would be through marketing strategies that help to increase organic traffic to your website.

What strategies have you found to be the most effective in increasing organic traffic if you have a website in a competitive niche? What should webmasters avoid?