Write an article based on this "Communicate with the person who hired you. Figure out what hours are best. Get to know the person you are working for. Ask Intelligent Questions. Get a Reference."
If you have to skip, or will be late, give them a courtesy call. You will need to have flexible hours for a good job. If it is a close friend, you probably can skip this step. This step is for your own safety. By figuring out more what the person wants, they will like you more, and usually get paid better. If you do a good job, the person who hired you can be a reference, helping you get another job!