1. Start psql with the database that you'd like to export from...
$ psql [DATABASE]
2. Toggle the output mode to unaligned (\a toggles between unaligned and aligned output mode)
3. Turn "tuples only" off (\t toggles between tuples on and off)
4. Set the output file (replace [FILE] with what you'd like to call your output file). It will send all query results to the file or |pipe.
=# \o [FILE]
5. Run whatever query you'd like to send to the output file. For example,
=# SELECT * FROM [TABLE];