Before designing landing pages you should know that 108 millions webusers are color-blind. Paying attention to colors is therefore really important.
We recently redesign our homepage at Elokenz . That was the occasion for me to recall how I designed the very first version. One of my colleague at the time was color-blind. This helped me to understand the importance of color contrasts for a great conversion.
Bonus : there is a list of pages that convert poorly at the end of the post. The post explains how to use Photoshop to avoid common pitfalls.