You can use surveillance skills to pursue a career as an investigator or to spy on whoever you like. You will need to have a mobile means of making observation and this might include things like pen and paper, camcorder or camera.
Learn how to be a Private Investigator. Learn surveillance techniques from a real private detective. This video covers the basic tools of being a PI and important features needed in your camcorder. This free video series will help you learn how to conduct a mobile surveillance.