Study your data, and not just the data from your social channels. Use Google Analytics to understand your website’s visitors, where they are coming from, what they’re doing on your site, etc. Use this data to tailor your social messages.
Track your competitors’ social channels and be aware of what they’re doing, discussing and who is interacting with them.
Media is looking to Twitter for story ideas. Take note of what media outlets or which reporters are following you, and message your tweets and posts accordingly.