Please have a look at our GitHub issues. Anything currently unassigned is up for grabs!
Once you find something you'd like to work on, please speak up and one of the admins will assign the issue to you. Then, make a branch appended with the issue number, ie, update-contributing-#101. When you are ready for a PR, please title it "closes" + the issue number, ie, closes #101. Please don't forget to include unit tests!
After you create a PR, one of the admins will review your code.
To get updates from master, we prefer merge over rebase.