Social media is all about conversations, and conversations mean that you talk and listen.

On Twitter, you can listen by:

Reading tweets. This is the best way to find out what is on the minds of your Twitter community.
Look for replies and mentions. Every time you check Twitter throughout the day, you should first check for direct messages and mentions. Mentions are public messages that include your Twitter handle and direct messages are private messages sent directly to you.
Search for your business name. Sometimes, people talk about your business without using your Twitter username. You should regularly check Twitter for people who mention your business name by creating a search and saving it.
You should follow everyone who talks to you on Twitter. So as you find people talking about your business or talking directly to you, follow them.