Do not panic! Remember that all college papers and most high school papers require double spacing, so take the number of pages required and divide it by two: that's the amount of work that you actually have to do, and it should be much less intimidating (unless you're in real trouble). 2.
Go to the library ASAP, or (if there isn't one open when you start) open your computer's browser to Google. Unfortunately, there's not really any way of writing papers without doing at least some actual work. Thus, you'll have to do some basic research, whether your paper's on Shakespeare or Capital Punishment. 3.
Think very broadly. Concentrate on the basic points of what you're supposed to say. For instance, if your paper is supposed to be on a Shakespearean play, get some idea of who the main characters of "Romeo and Juliet" are. 4.
For an English paper your opinion is just as important as facts. Use opinions to elaborate on ideas and explore various interpretations; a lot of marks can be easily gained by doing this. 5.
Check your grammar, spelling and punctuation at the end. A well written paper is more likely to make a good impression and convince the marker that you took your time writing it.
* Be careful: making broad generalizations is an art, not a science. Intuition and instinct should be your guide. Make statements that you know to be true but that aren't so blindingly obvious that your professor will feel you gasping for breath, so to speak. Being able to somehow feel when enough is enough on broad generalizations is a sixth sense that every slacker must eventually...