In a blog when you are referencing links to other sites within the content,should all of the external links be marked as a "do follow" link? What works best for good seo?

BUILDING SINCE 2012

"FFSK DIGITAL MARKETING" consists of young and dynamic professionals thriving to provide the widest spectrum of corporate service solutions in a single window. We are a professionally equipped company started with the mission to provide a comprehensive range of Management Consultancy Services to our clients.