Still, if you don't have the more accurate word in your vocabulary, then don't use it. It will sound stilted and unnatural in the context of your sentence.
That being said, for anything that you want to be sure your readers understand, "write like you talk". http://www.paulgraham.com/talk.html
Most people's speech (excluding times where they have carefully written it in a manner different than unprepared speech) not only isn't colorful, it's unclear by words alone, though often helped by tonal, pacing, and, in person, nonverbal cues, and, in interactive contexts, interaction with active audience members, all of which are lost in text.
“Write like you talk” can be good advice for people who are dealing with a couple specific problems (either a form of analysis paralysis stopping them from getting anything written, or habitual overwriting) but otherwise it's just bad advice that ignores the radical differences in medium.
People get caught up in the gravity of writing. I've seen amazing pub storytellers churn out unreadable dross because they think they need to be "literary". It's true that there are differences in the mediums, but they're not as great as people make out. Unless it's High Art (in which case everything is up for interpretation), it's all just transferring information from my brain to yours with as little spillage as possible.
Writers "speak" to us most directly when we "hear" their "voice" as we read. And some of the most atrocious nonsense I have read is by people who claimed to have "found their voice". You don't need to look for it. You use it every day. Follow that and you will avoid writing ridiculous, ambiguous things like "diversion of the field" when you really mean "sport".
This only goes for young kids in their native language.
In the other cases, it would just take too much time to get better at it, without that minimum of effort. (Which you might not be forced to do after high school.)
Not to mention that language is not just for communicating, but also for thinking.