BuddyPress.org

There is no real guideline apart from making sure your plugin is BP-aware.

You can check out how BP’s internal code is structured as well some of the most popular BP plugins.

A BP plugin is basically a WP plugin so you can also read up on WP’s general guidelines.

Also check out:
https://codex.wordpress.org/Developer_Documentation#Plugin_Development

BuddyPress Codex