Start with your friends and track down someone who works at your target company. Talk with the company's customers, read industry publications, and ask everyone you meet for the names of people who can give you more insight and advice about what it's like to work there. Build your contacts until one of them helps you get in the door. You will trust the human-resources department. When you approach a company through human resources, you submit to an administrative process that is once removed from the hiring manager.
Human resources is a graveyard of job applicants.
Never let human resources be the main conduit of information between you and the hiring manager. You will lose control of the process, and the likelihood that you will be dropped from the running increases dramatically when human resources is in control. Insist on dealing with the hiring manager directly. You will act like an applicant in the interview. After interviewing five candidates in the course of a day, managers commonly cannot recall much about any of them.