There are no formal educational qualifications to get a job as a contract cleaner. Most of the training and skills are learned on-the-job, including how to properly use and maintain equipment, techniques for cleaning various materials, and the correct way to store and use cleaning chemicals. Contract cleaners must pay attention to detail, work quickly and efficiently, and have a flexible schedule as cleaning may occur during nights or on weekends. ISSA, the Worldwide Cleaning Industry Association provides certification that can be appealing to employers.