When you turn 18 and graduate high school, more is expected from you. You're expected to know where you're going to college, if that's the path you choose. You're expected to know how long your program will take you and what kind of job you're going to have after you finish it.
After you graduate college, even more is expected from you. You're expected to know how to finance a car or how to apply for a loan on a home. Unfortunately, many forget that being finance savvy is not the only thing that you have to have a handle on in the adult world. There is much more to being an adult than just knowing your way around internet banking and Home Depot. It's about being a responsible and respectable person that is admired for more than what you own.
You need to treat others how you want to be treated. Actually, no, treat them better than you want to be treated. Show people that you are the person that will give them anything they need whenever they need it. Be someone that everyone looks up to.
"Adulting" is more than making adult purchases and going to your nine to five job everyday with little complaint. It's about owning up to your mistakes and accepting that it is okay to be wrong. You're not always going to be right and your opinion doesn't matter to everyone. It sucks, but it's a fact of life. Don't spread lies around about people and expect it to not get back to them because if you work with them or run in the same circles as them, it will. Be an adult and learn that not everyone is going to like you and pleasing people should not be your first priority. But remember, there is a fine line between being adult and being a jerk.
Being an adult means that if you have the means necessary to give, then give. Don't be one of those wealthy, stingy people looking back on your life at 65 saying "I wish I would have given back". If your town is looking for donors for a new library or activities complex, open up your checkbook right then and there. Give back to your community through volunteer hours or through your pocket. No matter which you choose, you're doing the right thing.
Recently I have watched adults all over act like middle school girls. Arguing about some of the most ridiculous and minuscule things that were made an issue all over their own opinions instead of facts. Let's not forget about the keyboard warriors out there. They love to spew their opinions like wildfire all over the internet but never have actual facts or resources to back it up and always refuse to be wrong.
To be an adult you have to accept certain things can't be changed and when that happens you just have to move on. Learn that the world revolves around the sun, not you and that will never change no matter how many tantrums you throw or lies you tell.