Here is a check list for creating useful bug reports:
1. Before reporting, make sure that you are using the latest version of the software.
2. Before reporting something as a bug, make sure it is in fact a bug.
3. Before reporting, play around with the bug to identify it with at least a bit of accuracy.
4. Report through the proper channel, usually an issue tracking system.
5. Make sure that the bug has not already been reported.
6. Invest some time to find a proper title for the bug.
7. State the name of the product in which you found the bug.
8. State the version of the product in which you found the bug.
9. Describe your environment (Operating System name and version, etc)
10. List the steps to reproduce the problem.
11. State the "observed result" of following the steps.
12. State the "expected result" of following the steps.
13. State the reproducibility of the bug. (Or your best estimate of it.)
14. Stick to the facts.
15. Address only one bug per bug report.
16. Include any useful attachments.
Here is a slightly more detailed discussion of each one of the above items: