No but seriously, I would advice him (5 years ago me) to start picking up skills that would be practical and useful in the next decade. And try to escape the small town he's in while the going is great, since the opportunity would have been exponentially more abundant.
I'd tell him the job he'd be doing for the next 4 years is useless and does not benefit him in any ways other than survival, which is a shitty way to spend his years.
Buy bitcoin and steem. Lots of it.
the advice i would definitely give to myself five years ago is that i should always ensure that they save at least thirty percentage ofy monthly income because that will make me to have a good savings and will make me have a more secure and stable lifestyle