I'll add the following to the original list:
DO indulge your inherent tendency to be as selfish as when you were fourteen, but dress it up like it's some sort of virtue.
DO distance yourself from the more painful aspects of reality, by making believe you are starring in your own heavy metal video, with dry ice and swords n shit.
DO continually tell yourself that you are actually a fierce independent Viking, preferably while working as corporate wage-slave, lining the pockets of an elite who don't know you exist and wouldn't piss on you if you were on fire.
DO stick with the comfortable viking cliche familiar from grade Z films, cartoons and comics, without troubling yourself with a more complex picture of Viking life that was as much about farming, colonising, trading and dealing with poverty and land pressure.
DO identify with the Vikings, as opposed to any of the scores of other ferocious dark-age/medieval warriors (such as the Alans, Visigoths, Vandals, Magyars, Jutes, Franks, Ostrogoths, Bulgars, Huns, Lombards etc etc) in order to show the boundless depths of your originality.
DO go on and on and on and on about being manly, and banging chicks and not being a goddam faggot, to such an extent that even the least analytical person realises there's something going on.
DO show your commitment to the intense berserker lifestyle by throwing yourself in front of a combine harvester, thereby sparing everyone else from your yawnsome adolescent bullshit.
Lifetime best: 500/363/573 @ 220 belt only
"The proper study of mankind is books" - Aldous Huxley