One of the hardest lessons to learn, and one that isn’t talked about much, is that as an entrepreneur of most types of businesses, your revenues reset each year. What I mean is that you have to sell a certain amount of your products or services the following year just get to the previous year’s revenues, and then some amount more to grow. Resetting revenues make growth difficult in tough economic climates.
This is also one of the reasons why business models with subscriptions, like software as a service or required maintenance and support contracts, are so desirable. Assuming a high retention rate (90%+), each deal sold in a new year represents growth as your revenue base is already the revenue from the previous year, if not higher due to more recurring revenue at the end of the year compared to the beginning of the year.
My advice for entrepreneurs is to look for businesses with a recurring revenue component.
David Cummings on Startups 