While Bridget Watson Payne's delivery in The Secret Art of Being a Grown-Up: Tips, Tricks, and Perks No One Thought to Tell You largely takes the form of cartoons and quick blocks of conversational narrative, I think most of her advice is sound. Here are a few choice nuggets:
Be suspicious of any kitchen tool that performs only 1 function (e.g., garlic press). [Obvious exceptions are the corkscrew and the Ham Dogger.] The Secret Art of Being a Grown-Up also outlines the tools you truly need to make yourself a functional kitchen that can even support a guest or two for dinner.
Go into nice hotels to use the restroom. Just don't tell them you're crashing their johns, or even ask where the bathroom is. Projecting "even a medium level of self-assurance" will get you far.
Look at the ends of your boxes of foil, cling wrap, and wax paper. See those perforated tabs? If you press them in the entire roll of foil / wrap / paper won't come tumbling out every time you move to tear off a sheet.
Additional grown-up topics tackled include the best way to open a champagne bottle, how to get a group of people to decide where to go for dinner, and how hard to watch out for credit card interest. Just in time for graduation, The Secret Art of Being a Grown-Up is a no-brainer gift for the boys and girls you know entering into adulthood (or those who should have crossed the border a long time ago.