You need to set up a place for the keys to go. Notice where you tend to go grab your purse or briefcase, or what you pass by when you're heading out of the house, and station a special place for your keys there. It can be a small bowl or a small plate, or you can put a little hook on the wall, but make it a special place for the keys to go — not just some place you toss them, but a special place. Because then you will know where they are, and be mindful of that.