Here is some basic, general information on what you will need to work overseas. However, information varies on a case by case, country by country basis. It depends on what country you are coming from, what country you are going to, your job description and your length of stay. Information also changes quite often, especially as security issues are becoming increasingly important. Therefore, it is always best to contact your local consulate or embassy, which you will need to do anyway when applying for your visa.