There are three basic rules for using turn signals:
1. Use them whenever you change lanes or turn.
2. Put your signal on before you start to change lanes or turn.
3. Cancel your signal after you have completed your lane change or turn.
Of course, there are other factors to consider when using turn signals, such as making sure they are working properly and using them in conjunction with other safety features like mirrors and blind spot checks. But following these three basic rules will help you stay safe and avoid accidents when changing lanes or turning.