As writers, it is crucial to observe our environments. Think about it – if you were writing a drama that took place in a prison, how best to learn the “lingo”? Daily survival tactics? What life is really like in the big house? You can either commit a crime and get sent to prison (not recommended), or interview current and former inmates and study written accounts of prison life. The important thing is to get first hand knowledge for authenticity. Even if your work might take place in an alternative universe, it would still be helpful to know details about actual prison life. You never know what might come in handy. This involves observing – digesting – any and all relevent information you can find.
Listening to the way people talk is also a great way to develop an ear for dialogue. I have been fortunate to travel around the country and just overhearing the way different people from age 2-100 speak - their vocabularies, slangs, rhythms of speech – has been an invaluable tool. I have used actual lines of speech in various stories and scripts that I have overheard or via people-watching. “Real” life stuff I never would have had at my disposal otherwise. In airports, restaurants, on city streets or in a rural “one-horse” town, it doesn't matter. Everywhere you go is an opportunity to take notes – mental or actual – to use as a reference. And, one thing I've learned, when you least expect it, you'll recall one of those characters or the way someone dressed or what he/she said, and it will fit it well with a project you are writing.
Many writers at the beginning of their careers don't do enough observing or listening to the world around them. Remember – as writers, we are constantly filtering our environments though us on a daily basis, whether we are conscious of it or not. Observe and Listen. You'll be a better writer for it.