I've mentioned before that few writers can do it all themselves. I'd like to extend that a little further by adding that regardless of the amount of research, it is next to impossible to get it just right.
So, as authors, I highly advise you go get in contact with people in the know. If you write police procedural, contact your local police department and see if there are any officers that would be willing to spend some time talking about how police work actually happens.
Just make sure you keep it clear that you are only researching for a novel. I may have been involved in a minor bit of confusion that ended up with the police chief requiring an interview...
If you are writing about fire fighters, talk to a fire fighter. If you are writing about soldiers, talk to a soldier.
If you are writing about dragons...well, talk to yourself. Don't act like you don't. We've all been there.
Someone knows better. You may have a romanticized idea of how a job exists that has been warped by TV, movies and poorly-researched novels. Ask someone in the know. You may be surprised at how willing the experts are to help you tell the story right.