When you report a problem, please submit one issue per problem. There are various reasons for this, amongst them:
The more crowded an issue is, the more likely is it that some problems may get lost over time.
Different problems are most likely to be handled by different people. The more problems you put into the issue, the more difficult is this issue to handle for all involved parties.
In particular, if you're going to write sentences like "Besides this, I noticed that ...." or "There are several problems with....", then please seriously ask yourself whether you should submit multiple issues instead of a single one. If you don't follow this rule, be prepared for people asking you to split up your issue.
Provide a meaningful summary
Providing a meaningful summary helps the committers to easily recognize an issue in a list of dozens of others. Since duplicate issues are draining a lot of work from committers, you should always check if the issue you wish to report hasn't already been reported. Of course this works best if the summaries of the existing issues are as descriptive as possible.
Provide a clear description
You, as the submitter of a problem, know exactly what you were doing when you were hit by the problem. However, most other people probably don't. For instance, they may have a completely different workflow for doing the same things you are doing.
In order to prevent committers to have to ask back how exactly an issue can be reproduced, it is the task of the issue's submitter to be as clear on this as possible - preferably by given a step-by-step description.