we've been unusually busy for the past 12-14 months (knock on wood) up about 10-12% over last year consistantly every month. this month had a little lull, but i just got married 2 weeks ago, and had been telling the regular customers about it, and tried to get jobs done before, or asked them to wait until a week or two afterwards (which all were OK with)
we did send out some emails to past customers that we haven't heard from in a while, and did a little house cleaning, and found some extra (new) banners stands, etc and decided to do a little sale on them. we also recently started offering business cards & postcards, and those have been selling VERY well. perhaps adding something simple to your lineup (such as the biz cards or postcards) is something you could promote year-round.
also, if you know every july is slow, start some sort of "advertising" in mid june to help boost sales the following month. or just get in touch with old customers, and make a sale!! take a few fridays off and drive around and check in on those customers and see how they are doing. more often than not, you'll catch a sale!
good luck!!