Making writing seem real means the story has to match personal experiences and what we’ve heard about, but that covers a lot of ground. Especially since no one will have experienced everything first-hand. That means that the main part you have to match is the impression of the subject that society gives us.
That’s why you can fake it.
For most jobs and places, stories rely on stereotypes. Societal impressions of what the job is like. The most memorable, well-known aspects of a place. Famous examples of a person’s behavior. That’s the sort of thing you can find out with a little bit of research or even from your own experiences with books and movies. And if you use those rough impressions, most people who are used to them will be perfectly happy to accept those ideas as true. Or, if they heckle a little, it won’t be any more than they do to every other story that uses those ideas. (It’s kind of like writing science fiction if you’re not a scientist.)
Take writing a character who is a cop. If all you know about cops is the impressions you’ve gotten from the news and other books/movies/tv shows, then don’t expect to write a book that cops are going to read for its gritty realism. That’s not gonna happen unless you’re willing to research for a couple of years (or have worked as a cop). But, if you want it to feel real to everyone else (people whose experience with cops more-or-less matches your own), then you just need to use the stereotype that everyone else is using. And thanks to the last decade or so of cop shows, you have a bit more variety to choose from.
That’s not going to make the details of cop work the highlight of your story. If you’re faking it, the details of being a cop are more likely to fall into the background so that the plot and characters can take center stage. Actually, that’s a good clue for when it’s safe to fake it. If the place or person aren’t the main focus of the story, then they only have to be realistic enough that they don’t distract (or detract) from the rest.
Here’s a little story to illustrate my point:
A man born and raised in the U.S. gets a job at the local Renaissance festival as a musician. He’s not very good at accents, but to sound more historic and European, he tacks on a “I’ve lost my lucky charms!” dialect and starts talking to people. People who come to the festival rave over his accent and ask how long he’s been in the country and where in Ireland he was from (*snicker*). At the very same festival, there was another gentleman who was not from the U.S. and had a genuine European accent. The people who came to the festival would tell him that his accent was awful.
Stage dialects are the perfect example of how faking realism can work! They are pared down, simplified versions of the real accent because most often the real accent is hard for people who aren’t used to it to understand (no matter what accent it is). Instead of trying to duplicate it, the actors try to suggest it, and that’s enough for the audience to know that the character is from Ireland or Russia or France or Brooklyn (wherever). In fact, we hear these stage dialects so much in movies and television that until we experience the real dialect first hand, we tend to think the stage dialect is the real one.
And that’s the funny thing about realism. It doesn’t have to actually be realistic – the reader only has to think that it is. That’s why if you aren’t an expert on a subject, and it’s not going to be the focus of your story, there’s a good chance you can fake it and still have believable realism. Believable enough for most people, anyway.