Most startup's are so concerned about running their business, they forget the importance of marketing their business. Or they are so far out of their element, they have no idea where to start. The huge mistake that most SMB owners make is NOT advertising. Perhaps it's due to budget, a basic state of being overwhelmed, etc. but it is a fatal mistake. You don't have to spend thousands, but the old adage is most certainly true..
"You have to spend money to make money."