When writing you should avoid the overuse of certain words. This doesn't mean you should NEVER use them, it means use them sparingly. Using them over and over becomes boring--and even humorous--to a reader. And if you have your protagonist in the midst of a serious romantic moment or at the height of a battle or in a life-threatening situation, the last thing you need to do is make the reader laugh because of your overuse of some word or words. Take the following, for example:
Sheawanda gazed into the man's beautiful eyes, and he gazed back into hers. They gazed at the
silhouettes of each others' bodies in the dim light, gazing across the sensuous curves of their
necks, waists, hips, and legs.
I'm going to assume that you have gazed long enough at the paragraph to pick out the overused word. Did it make you giggle? Or at least smile in amusement? I'm willing to bet that outcome is not what the author had in mind.
In addition to the above scenario, there are some common words that simply need to be avoided in general--not totally avoided, merely used in moderation. Here's a list: was/were, had, that, still, felt, noticed, saw, just, nice, thought, up/down, suddenly, really, dark, beautiful, almost, very, many, so. Keep them to a minimum.
Just because you want to just really say someone's beautiful, you can't just say nice things over
and over very many times, or suddenly you'll realize that you just noticed that almost all of the
really nice words were just suddenly sounding very funny.
YIKES! Does it make sense? Well, maybe. Does it make you feel like you want to read more of this person's work? Probably not. Are you getting the idea about overusing certain words? I sure hope so.