The ultimate situation is to also have a good high speed laser copier, preferably one with full optical duplication since digital has poor reproduction qualities with solid dark areas and photo images.  The copier should be used to produce the longer runs, while the printer is saved for generating the orignal or master copy.  This is both cost and time effecient since copiers are usually less expensive to operate than printers and are independent from the computer system itself.  High end, high speed printers are available, but the costs are often prohibitive.

You also need to be self-motivated, there isn't going to be a boss or supervisor standing over you to encourage you through your work.  Time and resource management skills are a must, and if you are not good with managing your time you might find yourself falling behind and missing your deadlines.  Use a scheduling system, pencil in your work hours as you would a job shift, then stick to it.  The prolonged periods of isolation while working on larger projects have a tendancy to dull some people skills, you are going to have to maintain good communications and relations with your customers and good people skills will go a long way.

One of the most important requirements is to maintain a catalogue of stationery products and samples of your work.  Most often you will be required to make contact with your customer at their place of business, so keep a well organized binder of paper samples and other examples available, include a sample listing of each font style.  This is your main sales tool besides your flyer or business card, which should be prepared to deliver a general description of the types of work you perform and kept in crisp, clean condition... dog-earred and soiled materials are unprofessional and leave the customer wondering about the quality they'll receive.