Let me tell you a secret about sales. The best time to make a sale is right after you've just made one.
This is true for psychological reasons-you're on an endorphin high, you're acting confident, and so forth. It's also true because by going right back into the trenches after one successful sale, you're continuing what can quickly become a habit of success.
Of course, most of use who have to sell (and this includes all business owners and entrepreneurs, consultants [that's me] and professional speakers [me again], not just officially designated "salespeople") do nothing of the sort. We ring our internal bell of happiness for making that first sale, figure our work is done for the day, superstitiously think that making two sales in one day is statistically unlikely (in the same superstitious way that people think that a coin that comes up heads is more likely to come up tails on the next coin toss), and so forth.
So we fail to ride that cresting wave. We rest on our newly acquired laurels. We busy ourselves with paperwork. We dig into another slice of pizza, feeling that, at least for today, we've done enough. We have our selling fix for now.
A better approach is to immediately--and I mean immediately, the moment you get back to the office (or off the phone) from that successful sales call--turn your new success into more success. Repeat it, build on it, keep the momentum going.
You'll be amazed how often one sale turns into two. Not every time, at least not immediately. But in the long wrong, in my experience, this "stay on the galloping horse" approach more than doubles your personal effectiveness in sales. Which will-guaranteed-make all the difference in the world.