The best thing we've done in the last year was start marketing, period. Previously, we made all our sales through essentially an enterprise model—get one national customer and pick up all their local affiliates. The sales cycle was long, and most growth happened word of mouth, but it wasn't fast. We had zero marketing presence aside from going to the relevant trade shows.
Last fall we finally hired a marketing consultant, built out a marketing website with a contact form, and are trying out some different pricing models. We've seen fairly consistent interest, which I'm reading as pent-up demand.
Lessons learned: I think the word-of-mouth angle was good for us at first. By keeping a closer control on our customers we were able to really make the product solid and understand the customer needs in depth, and how to segment the market with pricing and features. I wish we'd flipped the switch on the marketing website sooner, but there were benefits from waiting. The number one lesson if you're going to do that is give potential customers who hear about you a way to contact you—otherwise word of mouth has zero benefit. (I realize these probably seem obvious to most, but our market is a little niche and knowing that we wanted to market primarily to the national customers instead of their local affiliates pointed us in certain directions early on.)