What is Brian Halligan's advice for effective Facebook and Instagram marketing?

Brian Halligan emphasizes the critical importance of establishing a strong presence on both Facebook and Instagram. He advises marketers to build large, engaged communities on Facebook, where 'people live their whole lives,' and to extend that presence to Instagram, where you need thousands of followers rather than hundreds. Halligan stresses that success comes through focus and excellence rather than spreading efforts too thin. His key recommendation is to not just be good at social media marketing but to 'get great at it' by focusing deeply on these platforms and mastering the hard aspects of digital community building. This focused approach aligns with his broader philosophy that the most successful people say 'no' more often and excel at difficult tasks.