Getting a hiring manager to return your phone message. Far too many jobseekers, use the same phone call etiquette as they would to a friend or family member who knows who they are. Little thought is given to creating a message that will be returned by the employer.
For every 30 job applications I receive one generic rejection and the rest are ignored. My inbox now almost gives me a sympathetic smile and braces for the worst each time I excitedly open an email from a prospective employer. From my endless applications I have only received feedback twice which vaguely informs me that the company loved my personality, but they've selected someone with more experience.