An author who goes to book signings, speaking events, or libraries benefits from having business cards to hand out, flyers or posters to advertise, maybe a banner. For everyday, it's useful to have professional business materials include letterheads, postcards, etc.
materials can be costly, and some companies only give good prices if
you order hundreds or thousands at a time. Who wants to be stuck with
2,000 flyers, especially if, after you get them, you find a typo, or
want to change information? Yikes.
Making materials has helped my sales. It has helped me develop a brand and present myself as a professional.
a video I made on creating a brand, and my favorite place to go to find
inexpensive (they're always having sales!) and sometimes even free
(I think I was tired the day I made this, so just pretend I'm smiling through it. =))
Creating consistent materials are a great way to present yourself as a professional, advertise your work, and spread the word! Just sign up for their e-mail updates and you'll start getting the great sales.