Never use a long word when a diminutive one will do.
In general, I use short, common words rather than long, obscure words whenever possible. Some people like to use big words because they want to impress the reader with how smart they must be to know and use all these big words. I've had documents I've written for my company where an editor who came after me in the process went through and substituted long words for all my short, simple words. Like changed every occurrence of "use" to "utilize" and that sort of thing. If you ever find yourself thinking like that, stop. The purpose of writing is not to impress the reader with how smart you are, but to convey information to the reader.
Of course this doesn't mean that I never use long words. Sometimes the long word is more specific than the short word, or more precisely conveys the intended meaning. Sometimes I'm looking for a particular rhythm in a sentence. A long word can slow down a sentence, and thus help to add just a little bit of tension before springing the last word.
Side note: As Kit says, "lit" means to set on fire. You should say "lit up everything around them", not "lit everything".