Assembly instructions is an important means for supporting operator performance in final assembly. An operator at a production line, whether experienced or novice, will encounter situations that include the assembly of new products or new variants. Instructions that are developed without consideration of these processes can cause unnecessary cognitive load and lead to poor operator performance. This paper describes an experiment that shows that assembly instructions can increase operator performance and presents nine simple guidelines. The Importance of including the operator view is stressed and how the guidelines should be implemented in practice is discussed.