Make sure you've read and understood the code style for the PR's. The
changes that don't follow the code style will be rejected. Read
README.md in the Source folder for more details.
Make sure the PR, you're sending out, is expected by the maintainer(s). A small fix of couple of lines can be simply sent out, but anything bigger requires either an issue in the tracker, or the maintainers/authors pre-approval.
Always provide a brief description of the change and its impact to the code. If the change is not backwards compatible, it must be explictly pointed.