Remember to focus on your logo, but also keep in mind the fact that you need to have a unified look throughout your corporate identity (envelope, card, stationary). One method of achieving Unity across multiple pieces is by incorporating and utilizing similar fonts, colors and elements from your logo into the corporate identity. Don't forget about the narrative behind the logo.
Keep things simple. Before you start on the computer set your color scheme using Pantone colors that convert well to process (CMYK) color. This project should be created in Adobe Illustrator.
Here are a few of links that showcase creative logo and corporate identity design:
75 inspirational business cards
thedesigninspiration.com
www.cardonizer.com
3 Quick tips for Great Logo Design
The two sites below will require sign up to access all the features. Logo lounge will require membership fees for full access, but they do have free resources for designers on their site:
bamagazine.com type logo download
www.logolounge.com
Below are some links for a color guides and quick reference sites:
Color guide quick reference
colorschemedesigner.com
Adobe Kuler