Whenever possible, use the following contact methods;
they allow verification to mitigate man-in-the-middle attacks,
have solid security, and reasonable privacy.
Use the keys for each contact method to verify my devices.
Note that verification does not verify a person, only their devices,
and can be defeated via coercion or other force.
If metadata leakage is an issue for you, you can use the following
contact methods. Note that these services do not have verification
functionality, and will be treated as less secure.