Throughout the entire educational system you are surrounded by your peers, people in your same age range with similar experiences. Sure there were adults to interact with, however they were being paid to be nice to you and interested in what you have to say. Once you leave the educational system you are thrust into a much wider age range for the first time in your life. People you work with and interact with will now run from 18 years old to 65+ years old. This means that you will need to know how to interact with this new group in order to be as successful and influential as possible.
When you are just entering the real world from academic life, humility is often your ally. Learning from those with more experience is a valuable skill to have during the first few years in the professional world. However humility can have a negative side as well. An important thing to remember is that adults are no longer a source of authority like professors were. The adults you have interacted with so far (teachers and professors) have been the source of knowledge within a closed system. They have mastered that environment and can be relied on to provide advice for how to proceed within the academic setting. This is no longer necessarily the case in the real world.
One thing that is important to understand is that adult life is no longer structured like academic life was. You are able to make your own choices and become whatever you would like to. Every single person is in the same boat as you are when it comes to knowing how to make that happen. Learning from others now becomes a much more interesting prospect. You need to choose role models and advisors that have accomplished what you would like to accomplish in circumstances similar to your own. This can be frightening or liberating depending on your preferred work method.
When dealing with adults in the workplace it is important to be respectful and create positive relationships with co-workers and business connections. There are certain relationships which can be improved by using a lighter demeanor however for the most part, when meeting someone new, it is best to do so in a professional manner. This means no cursing, no slang, and as little sarcasm as possible. It sounds like what all adults have been telling you for the longest time, but the truth is that you will be better off doing things this way until you have more experience navigating the professional world.
In adult life everyone has their own issues to deal with and may not be as willing to help you out with your current problems. It is important to learn to be self-sufficient and begin to solve your own problems as they arise. This will be one of the most powerful tools that you can cultivate moving into adult life. Adults respect those that are able to handle their own issues and can then help others. You will gain respect and become a figure of authority among those that you interact with on a daily basis. This will set you up for success in both professional and interpersonal matters.