The wording and design, from typeface to the color, weight, and even texture of the paper, all subtly shape how your wedding will be perceived. If you're planning a casual beach wedding, for example, then that should be conveyed from the start in the design of the invitation. On the other hand, if you picture your wedding guests in tuxedos and floor-length gowns, then the invitation should be equally formal in tone and style.
There are no hard-and-fast rules about design--above all, it's important to create something that you like and that reflects your wedding plans. However, some guidelines will help you sort through all the options: