When you accept a job, you go into partnership with your new employer. You agree to do a job for them, and they agree to pay you for your services. It's to both of your advantages to work out the job details as quickly as possible so that you can "get on with it."
Focus on asking and learning. Your first few days on the job, focus on asking questions of your boss, your coworkers and subordinates. In most instances, even if you're the new boss of the whole department, you aren't expected, and frankly shouldn't, begin to completely revamp operations on the first day. There's too much danger that you'll end up throwing out the baby with the bath water. Regardless of what you were told when you were hired, most of the employees are probably competent and trying to do their jobs. During the first few weeks, find out what they are doing and observe who's doing it well. Find out as much as you can. Assume the learner's role, and let department employees know that you appreciate their help. Do a lot of managing by "wandering around."
Investigate and ask about duties and responsibilities. If your new employer doesn't make arrangements for your training, you'll have to take the bull by the horns yourself. Introduce yourself around. Ask if anyone else has essentially the same kind of job. If so, ask them to describe their job and how they approach their work. Ask them to show you how they do some of the specifics.
Look for written job descriptions, training manuals or handbooks, catalogs of the company's products or services. Read everything you can find about the company and the department. Find out what the department's existing goals and objectives are and its purpose for the company. If you're at a higher level, find out what goals and objectives were for the preceding years, and what has been already set for this year. Find out if the company has any purpose statements. Investigate the various budgets for which you're responsible. In short, find out as much as you can as fast as you can.
Determine formal and informal power structures. A first order of business is to find out about the reporting relationships in your department, division or company. Who reports to whom and how is the company structured? What do the organizational charts look like? Get a copy of the company policies and procedures, if one is available. If these are not written down, find out what policies and procedures are understood.
In major companies, you'll likely be given an orientation session and a booklet or employee handbook describing the company, the benefits programs and the basic corporate personnel policies. If the company doesn't have these policies and procedures in writing, ask to discuss them with your immediate superior so that you won't make mistakes. Then take complete notes to use for reference purposes.
In addition to the formal power structure, every organization has an informal social structure that wields a good amount of power. What are the social norms for the organization? Who's friends with whom? What about coffee breaks, lunches, general socializing? Make an effort to be friendly, to become acquainted. It's tough to ease into a group. You don't want to be considered standoffish, but neither do you want to blunder. The best way to begin is to observe carefully. With whom do you seem to have rapport? Which people seem to be the key players, regardless of their job descriptions and formal titles?
Notice who talks with whom, who appear to be the advice givers and the advice takers. Meetings are an excellent opportunity to get a feel for these arrangements. Who sits with whom, who speaks up and commands attention, who speaks up and gets groans (or inattention). Unless you're in charge of the meeting, you're better off observing the first few times before you begin to speak out.