There's a great little thread on Reddit.com with a list of Life Hacks--short cuts that will make you more efficient. A few of the best are:

1.  Make a note on your phone called "birthdays."  Whenever someone mentions something they like or want, write it down in there . . . or you WILL forget it.  Then when it's time to buy them a gift, you won't even have to think about it.
2.  If you have to go to the bathroom in the middle of the night and need to turn the light on, cover one of your eyes.  That way, when you go back to bed, the eye you covered is still adjusted to the dark and you can see where you're going.
3.  Open bananas from the bottom.  It's easier and helps you easily break off the nasty bottom part.  
4.  When you're brushing your tongue . . . or doing anything else that might make you gag . . . make a fist with your other hand and tuck your thumb into it.  Squeezing your thumb reduces your gag reflex.
5.  When you wash your hands in a public bathroom, spend about 10 seconds shaking the water off your hands over the sink.  Then take one paper towel, fold it over, and use it to dry your hands.  You won't need more than that.

Here's the full thread:
http://www.reddit.com/r/AskReddit/comments/1vis3s/what_life_hack_do_you_use_all_the_time_which_one/