A good technique is to choose a few activities during the day to do reality checks during. Like every time you use the bathroom or open a door or turn on the TV, etc. You don't have to dream about these activities for this method to work.. the idea is that you get practice in remembering to do them during the day, and that should translate to dreams. After getting good at this, you can try saying something like, "I will remember to RC in my dream" before bed.