A simple way to stretch the life of all your clothes? Skip the dryer. All that heat just isn't good for your clothes.
Clean dirt and scuff marks off of your shoes as soon as you notice them to avoid any permanent damage.
Food spoilage is often the result of improper storage. Learn how to store the foods that you eat regularly:
Stick candles in the freezer for a couple of hours before you use them. This will cause the wax to burn slower and more evenly.
Follow the manufacturer's recommendations for flipping and rotating your mattress to prevent premature sagging.
Vacuum the condenser coil every three months (once a month if you have pets).
The simplest way to extend the life of your printer ink is to only print what you need, but that's not the only thing you can do:
Revive dried out markers by storing them vertically (tip down) for a day or two. If that doesn't work, try dipping the tips in alcohol for a few minutes.