The phone has become an underutilized sales tool, says Ilise Benun of Marketing Mentor. Emails and tweet lack a human touch, she says. So think about dialing the next time you want to reach a sales prospect. But before you pick up the phone, do your homework and determine how you can best help your potential customer. Make sure you leave a customized message in the likely event they don't answer -- and follow up with an email. Lastly, don't worry about being annoying, as you may be calling someone just when they need you most.