Another thing is to have a great telephone manner, and be very confident when you speak to customers. Go out and see them face to face rather than giving a price on the phone. Then once you're there you'll practically always get the job.
There's a load of 'pest controllers' out there, too many in my area now, but the tide is turning and many are giving it up as they cannot make any money, never mind a living. But you'll never know unless you give it a go....