Business stationary usually consists of letterhead and an envelope. I have my letterhead set up as a template so I can add it to any more official digital correspondence, but if you have a lot of printed correspondence then it would be good to have printed versions. You could then insert any printed letterhead into your copier or printer to get a clean official looking communication. It is your choice how you use a letterhead and if you would even use an envelope but every business needs to have a branded look to all communication.
You can learn how to create your own business stationary in Adobe Illustrator in Your New Business Card which also covers developing coordinating letterhead and envelope. There is a discussion on postal regulations to consider for envelope design and some ideas on how to layout your business stationary with step by step instructions to layout all in Adobe Illustrator.
It is hard to get inspired to create business stationary for even experienced designers. I suggest looking at examples of your competitors, and other professional examples to get your creative juices flowing. I am posting a couple links I found with very creative designs. Yes, some might be a bit much but all this creativity will certainly kick your vision into high gear for your own design.
Whether you are just going to use your letterhead digitally or have it printed having that fully branded look will be a solid professional way to present yourself and what you have to offer.
Next week we will dig into envelope sizes.