Purchase an external hard drive or two to backup your files on once every other week. There's no mess with floppy disks or CDs, and you can even take it off-site with you.
Never use the same password for your email address at any other site. Have multiple passwords.This will ensure that even if the sites data is stolen your email is not compromised.
Make sure you set up your power management settings to put your computer in standby or hibernate if you walk away for a long time. It will save you a few cents, but over time it can add up.
Turn your computer off at night.
To have a safer internet at home use opendns.com. It's free content filtering and blocks malicious sites."
Don't be a social network junkie. Try to divert that time and energy to do something productive. Try to learn one new thing each day. You will be amazed how many really interesting things there are to learn.
Secure those wireless networks! secure preferably with WPA, MAC filtering, disable SSID Broadcasting, change the default channel of signal, change default admin username and password.
If you need to light a pathway to your house, use solar powered LED ground lights. They don't rely on electricity, and can save you money. plus, there are some models that look great.
Don't go for the first software you find as a solution to your need. Look for others and most probably you will find one that is free and costs you nothing.
Instead of paying $25 to $50 for an book on CD or $10-$25 to download one, you can find hundreds of legal free audiobooks to download on librivox.org or podiobooks.com
Learn to use keyboard shortcuts... using your keyboard to copy and paste, quit applications, open a new tab, etc. will save you time and frustration.
In Windows, Alt+Spacebar opens a menu for the active window, allowing you to minimize, maximize, move, size etc. without using the mouse.