Learn the specifics of the assignment. Don't get too ahead of yourself. Pay attention to the teacher's verbal and written instructions. Sometimes, especially in grade school, the instructor will have incremental assignments, as opposed to just turning in the paper by itself in the end. For instance, note cards may be due one week, followed by a rough draft the next. The worst thing you can do is to write a brilliant paper that gets a poor grade because of format issues. Also, this step will help you in determining your focus.
Do the research, and organize the information. The library or the Internet are popular and effective places to get started, but don't be afraid to dig deeper. For example, consider interviewing people you know who have significant experience in dealing with negative consequences of losing their temper. Also, spend a lot of time studying celebrities, sports figures in particular, as they often make headlines with tales of anger-based behavior.
Write a draft of the paper. Include a good strong introduction that sums up what the paper is about and why it matters. The key is to draw the reader in. Granted, it probably isn't an assignment that will be published on the web where you're competing for viewership, but the teacher will no doubt be looking for an intriguing hook. In the body, list a wide variety of consequences backed by examples. In addition to the aforementioned media and personal examples, address what those who lose their temper have to do to mend fences and conduct damage control.
Make revisions to your draft. Start by looking for any obvious grammar and format errors, such as typos or style mishaps, respectively. Then, go over the finer points by ensuring that everything is clear, parallel and concise. Basically, your research should be well discussed and organized without being to wordy. Consider taking a few hours or days off from the project if time permits. The longer you spend away from it, the more clear-headed you'll be when you come back to it, as opposed to obsessing over it in one marathon session.