Understand how computers and peripherals work. You can avoid throwing money and other natural resources at computer problems by understanding how they work. Maybe you don't need more memory or a new hard drive after all. Learn how to do basic repairs and maintenance. There's nothing magical about the insides of your computer.
Electricity goes in, runs around turning switches on and off, and information comes out.
With a screwdriver or two, you can replace a card or hard drive, vacuum dust, or retrieve a disk stuck between two drives. Add some soldering skills and you can do even more. With practice, you can even do creative repairs. For example, my power supply fan quit, and the manufacturer doesn't sell replacement fans. So I looked inside the power supply.