It often takes the same amount of time and effort to close a $100,000 deal as a $1,000 sale, so go where the volume potential is by focusing on the big accounts. Segregate your prospects by good, better and best, based on their dollar level. Spend your time on the largest and best.
It's also a good idea to spend time with a good mix of prospects, including small, medium and large, so that the lesser-sized sales fill in the gaps between big hits. Then, when you have more time, work with smaller accounts to find the ones with the most potential.