It's tempting when you have an overburdened schedule, or if writing isn't a comfortable task for you, to wait until the last minute to write a paper. Giving yourself plenty of time to research and write your paper reduces the risk that you will resort to plagiarism or use another's words without meaning to because you are rushed and exhausted. Set a schedule, breaking large papers into smaller, more manageable tasks such as writing an outline, researching specific parts of the paper, writing a rough draft and revision.
If you have rewritten an idea or piece of information, but added nothing of your own thoughts, you must cite the source of the original idea or information. If you don't, you are plagiarizing. Sometimes it may seem as though you have written something original, because you aren't using someone else's exact words. But if you are using their ideas or data, you must give them credit. In your paper as a whole, it is important to make sure you are not simply rewriting other people's ideas. Make sure you use their data to come up with your own conclusions.
When researching for a paper, make sure to take accurate notes. One way to do this is to write notes on index cards as you read and write a citation on each card so you don't forget. Writing the citation on each card avoids the problem of having notes but not remembering where they came from. Writing one idea or piece of information on each card allows you to arrange the cards as a way to organize your paper as well.
Make sure, when you are writing your paper, that you cite everywhere you are supposed to and that you cite properly. The citation goes at the end of the information you are including in your paper. Placing it too soon may result in unintended plagiarism.