Here is a great tip that I came up with out of "desperation": I love to peruse craft websites and print out free directions for ones I want to do later. Well, one day I went to print out a couple and found I was out of printer paper.
When I make a mistake when I copy something, I cut out the part of the paper that is blank. Any mail I get that has parts that have blank areas, I cut it out. I now have a drawer full of paper that I use for notes, shopping list etc.
If you use a lot of paper printing information from the internet, you can save on paper by using the blank side of handouts from work and school.
Don't throw away computer paper that has been used on one side! My kids love to use this paper for drawing, etc.