“Essentials” lists abound, especially online; the shoes a man “must own,” books he “must read,” places he “simply must visit.” Most of the enumerated essentials are anything but. Some change daily.
Still, some things are much closer to mandatory than others. For instance, always vote your conscience and inform your choice; don’t be swayed by irate volume. Exercise. Also, cultivate a preference for the tasteful and refined over the loud and garish. Appreciate family, friends, and food. Read good books.
Be polite. Ask other people about themselves, and listen to their answers.
A step further from necessary, but still likely good ideas: watch The Godfather. Go to museums. Develop at least a passing knowledge of the mechanics of guns. Spend time outdoors.
And if there’s still time: know the difference between a sport coat and a blazer. Pick up squash. Reconsider how often wearing socks is really necessary. Wear clothes that fit. Don’t wear square-toed shoes; you’re not a ninja. Don’t wear athletic shoes with pants, and invest in some good stationary.
Though not essential, some of these things are close, and all are worthwhile.