Step1: Develop a checklist of your home (Take a pen and paper and walk around your home, and list access ways i.e doors & windows which require you to secure that feature prior to departing your home.
Step2:For the first two weeks continue to check all the access points prior to leaving your home or going to bed at night and tick them off your list & say out a loud the word "CHECKED".
Step3: By the end of the second week, you should have the layout of your home programmed in your mind, and you will not need a list anymore. The securing of your home will become second nature, and you will feel more confident and self assured that you have 'locked the house'. No more second guessing or worrying about "did I, or
didn't I lock the house?"