The first and foremost fact you need to keep in mind when dealing with your boss is just that; it is your boss, not your friend. Your boss is the person whom holds your career literally in their hands. It can be easy to get in to a situation where you would rather become friends with your boss, this is not a good idea as personal lives can overlap business and if you cannot keep them separate, and you may be in for heartache or job loss in the future. This can happen when there is a falling out between you outside of the work place. By not getting into that type of position, you will not have to worry about your personal life impacting your professional one.
If your boss is more of a relaxed type of person who does not require the respect many in authority do, it is still important to keep your relationship with him/her strictly professional. Your boss may have no problem speaking about his wife and children to you or perhaps asking your advice in these matters. You are within your rights to give your advice, but do not let out any of your own personal information as this opens the door for a personal relationship. By staying professional at all times, you will put forth an attitude of respect for your employer no matter what the situation may be.
On the other hand, you may have a more militaristic type of boss whom demands and commands respect at all times. This will be the employer that can make many people nervous, even afraid of them. While staying respectful, keep in mind that the boss is only a person like you and that you should not fear to speak with them when you have an issue. By maintaining the respectful stance they require, you should be able to communicate effectively with them.