Keep a binder of your important documents with tab dividers labeling what they are.
Getting organized with your important documents makes things less stressful the next time you begin digging through random boxes searching for your social security card (if in the US), birth certificates, car insurance information, or even your passport.
More General Tips
Use a paper plate and clip to boost your flashlight beam in the dark.
Narrate tasks out loud if you have trouble remembering whether or not you completed them.
If you keep forgetting that you closed the garage door, when it closes, say out loud: "The garage door is closed". Or when you wonder whether or not you unplugged the iron. "The iron is unplugged". Your brain will become more stimulated to help build a stronger memory.
Good work ethic requries good rest ethic.
"Work hard, play hard" is probably the most mainstream version of this ideology, but it's absolutely true, in order to be a top performer at anything. The most productive people regularly take a step away to process what you are doing and plan out where you are going. It also helps avoid burnout.
Want to stop walking into people on the sidewalk and in crowds? Avoid eye-contact.
Staring directly at your destination instead of other people in the eye will signal to them to get out of the way.
Use your hand as a ruler.
Measure your hand from your fingertips to palm and memorize it. Now you can judge the size of anything without a ruler. Try to pick a finger that's pretty close to standard length (~1 inch).
If you have to remember to bring something with you, place it next to your shoes.
You'll never forget it. Place it inside your shoe if necessary.
Wishing things were different is a great way to torture yourself.
No time is better than the present to make changes. Stop thinking in the past and continually look forward to the future.
Don't cheap out on what you put between yourself and the ground.
Shoes, tires, beds, office chairs, couches, etc. You will thank your future self for doing so.