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.
Don't throw away computer paper that has been used on one side! My kids love to use this paper for drawing, etc. Also, I use the paper in my computer printer when I print out things like grocery lists.
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.
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.