If you are experiencing a problem, the recommended way to proceed is to submit a Problem Report (PR) via the webpage or via send-pr(1). There is a set of guidelines you should read if you are not yet familiar with them.
If you are interested in working through existing bugs, you may wish to query the PR database, or join us on IRC on #freebsd-bugbusters on EFNet. You may also find the PR Handling Guidelines article useful.