I have been a cop for over 30 years now.
The evolution of your career depends on you. I've made a ton of mistakes along the way, but when I show up on a scene people, good and bad who know me know that I am going to deal with the problem and be fair and firm in my actions. And yes, when the bad guys see me coming, they know it's time to go somewhere else. They know they lose when I'm the one doing the dealing. Period.
I have people I do not know coming up to me to tell me "stuff". I must have a good reputation, because a lot of the guys that I work with are always asking me "how do you find this stuff out?". I do not know. I just treat people the way I want to be treated. Give some respect, you'll get some respect.
DO NOT isolate yourself from the rest of the world. Have other friends besides other cops. I actually hang out with very few of my police friends anymore. But the few I do associate with are lifelong friends whom I have been to hell and back with on more than one occasion and whom I trust implicitly, with my famliy, and my life. Again............. very few.
When I'm off work, I'm off work. Period. Unless there's a felony being committed in my presence, at which time I am compelled to act by Florida statute, I just pick up the phone, quietly and while trying not to be noticed, and wait for more troops to arrive and let them deal with the problem. I do not want to be having to go into the office on my off time to write a damned report. And yes, I do carry my weapon off duty, and handcuffs too, because there is always going to be that 'one time' when if you don't have them you're going to need them, and if my family is with me, their safety is of more importance to me than anything else in this world. So be prepared.
Whatever​ happens at work usually needs to stay at work. But not always. There will be times when stuff happens that afterwards, you just have to talk to somebody else about just to keep your sanity in check. But if you're going to talk to somebody, talk to family, your agency chaplain, somebody you trust, and if possible, somebody away from "the job".
Don't get caught up in that age old cop game of drinking and crying in your beer over stuff that is totally not worth rehashing after work. And don't drink too much and make an ass out of yourself in public after work. People are watching you, and what they see can help you or hurt you down the road. Other people talk, sometimes to your superiors, and bad news always travels fast, espcecially when you're the focus of it.
Just be a normal human being. Develop other interests besides police work. Laugh, love, and live life. It's too damned short to not live right, or to make so many mistakes that you will regret years later.
This is me......... now. I wasn't the same person I am now when I started on this job. Time and experiences do that to you.