Determine what information is needed on the card and letterhead such as company name, logo, name of individual, title of individual, street address, mailing address (if different), phone number(s), fax numbers, voice mail or pager numbers, email address, and web address.
Begin sketching out ideas. Explore layout options quickly with rough thumbnail sketches.
Layout
Look at other business card layouts for ideas and inspiration. For business cards, horizontal layouts may be more "traditional" but vertical layouts could provide more opportunity for creativity. Additionally, it may be easier to translate the vertical layout of the business card to the vertical layout of the letterhead. I'm not suggesting that you should only consider vertical layouts though. It depends on the shape and orientation of other elements of the design as well as the image you want to convey.
These Horizontal Layouts and Vertical Layouts and Business Card Templates provide tips and ideas for business card layout. In some cases it may be easier to work simultaneously on both the business card and letterhead.
Robin Williams suggests that you should stick with standard size business cards but that making them foldover cards will allow the business card to do more than just list contact information. They go from being just identity items to mini-brochures and more powerful marketing weapons for a business.
Don't skimp on the envelope design. Putting beautifully-designed letterhead into plain, off-the-shelf envelopes dilutes the power of that first impression.
Beyond the layout, you'll need to make decisions regarding fonts, color, paper, and methods of printing.
