Some sample strategies to adopt:
1) Mobile sites only, never apps. Always log out when done to increase the friction of subsequent logins. The most insidious pattern of mindless engagement is when you're bored at the checkout line, waiting in-between meetings with nothing to do, sitting on the toilet.
2) Even better: computer access only, never mobile. Your phone is always around, unlike your PC. Set a time slot (20 min or so) when you know you're around your computer. Social networks really excel at this pattern of usage. You'll get the most important stuff, fluff relegated to the bottom of the feed, which solves the FOMO and shield you from the rest. This can be daily first and then cut down to whatever pattern you feel like (Newport himself claims he catches up on social media once a week).
I am sure I am butchering some of his advice, so worth reading the book.