Send people condolence messages privately and quickly. It does not matter what you say exactly, but reach out and make sure they know you are thinking of them.
Eat your vegetables. Or whatever thing you used to refuse to eat as a kid. There are so many tasty things out there and if you stay set in your ways and never try new things, you'll never know. There are things I don't love, like sushi, but at least I've tried it and know I don't prefer it.
Don't be afraid of the hospital. When people are unwell (and it is appropriate to visit them), go. They are the sick ones, go and see them.
Thank people for a job well done. Whether that is someone serving you food, a co-worker, or someone in your family, say thank you. Little notes or words mean a lot.
Read the news. Don't be ignorant to the world around you. I don't read the newspaper cover to cover, or watch the news every night, but I stay informed by listening to the radio, following reputable sources on Twitter, and checking Google News to see what's going on. This helps you carry on conversations with the other adults you'll run into throughout the day (and understand how to explain things to the kids in your life too).
(No good photo to add to this post so just a photo from Barcelona!)