Follow people who are interesting and useful -- ideally both.

Look at your competitors, friends, business colleagues to see who they are following. Look at what they say. See if you care.

Sometimes someone "matters" to your business even if they aren't especially interesting because of their position. It might help to know that a prospective customer is in town, so you can tweet, "Want to meet for lunch?"

Think of Twitter as a radio. You can tune in and listen to whatever station interests you.

(Note: I co-wrote a book about Twitter for business. That might make me more reliable... or less. :-) )