There's a fine line to walk--you don't want to overwhelm a reader, but you want them to get the impression that you as a writer know what you're talking about. And more, you want to creating setting, mood, and accurate characterization through these word choices.
I just finished reading a super-fabulous historical, Surrender the Heart by MaryLu Tyndall. One of the things I expect of MaryLu's books is a wonderful knowledge about tall ships and seafaring, and she knows how to strike the balance between showing me the details of a ship and not making my eyes glaze over with it all. I closed her book and thought, "Wow. She obviously knows her stuff. She imparts her wisdom. The characters come across perfectly. And I shiver at the thought of ever writing anything on this topic, because how in the world would I keep it all straight?"
And though, yes, I deal with this issue in historicals all the time, the first story to pop to mind when I contemplated it was my contemporary, Seized. My hero is an ex-SEAL, so he uses military jargon all the time among his friends.
Now, I'm an avid watcher of NCIS (and was of JAG back in the day), so I at least know TV jargon. =) Not exactly dependable research, but they're pretty good at establishing setting and mood, anyway. I read a lot. I visit a lot of websites when I'm researching something. But I'm never quite sure I'm getting the jargon right until one of my critters goes, "What are binocs? Binoculars?" and I lift my brows and realize I hadn't even intentionally peppered that particular shorthand in. I like it once that starts happening, when I can stop thinking about it so much and just let it flow.
Stop for a minute and think about some of your favorite books. When I do, I realize they all have this jargon-thing in common. The characters are so very much themselves that they think with these words, use them to make unique-to-them analogies, and convey a definite image. How about your favorites?
Hope everyone had a safe and fun weekend! My little fairy and turtle were adorable and polite as they skipped around the neighborhood, so I'm a proud mama. =)