The latter: send requests and hope people follow you back. Twitter
doesn't encourage mutual "friendship" as much as some other social
networks. It's okay to follow and unfollow people as adjust the
amount of tweets per day that you're comfortable with receiving.
For questions like this that don't directly pertain to developing
Twitter applications, please see our support site:
http://help.twitter.com/
--
Alex Payne - API Lead, Twitter, Inc.
http://twitter.com/al3x