I Didn't Learn Everything I Needed To Know In Kindergarten

They told us how to share, count, and read/write (hopefully). They didn't tell us that everyone also needs (eventually):

A credit card
A good lip balm
A tool kit (with the works - wrench, hammer, screwdriver, etc)
Cooking skills
Tolerance for incompetent customer service reps
An Indian broom
Internet connectivity

I'm still setting up my new apartment and have found these things indispensable. Customer service generally sucks and the rep will ignite in you unprecedented rage, free-of-charge. Is a good lip balm really necessary? you ask. Um, yes. The indoor environment is as dry as a desert and you will not survive without some.

Also, know your tools. Furniture that requires assembly doesn't come with tools, so know 'em. The doorman won't know the difference between a wrench and a plier. Mine didn't. But he was 6'2" and I just didn't have the heart to tell him so.

Swiffer is overrated (although still loveable) - get an Indian broom to sweep well. It's practically a workout, too.

I'll forgive the last one since it didn't quite exist yet when I was in kindergarten.