“Not that the story need be long, but it will take a long while to make it short.”
— Henry David Thoreau
“So the writer who breeds more words than he needs, is making a chore for the reader who reads.” — Dr. Seuss
Half the work of writing is cleaning the manuscript afterwards. Writers tend to write long and use way too many words (I could have omitted "way" right there, as an example). So once you hit the lovely "The End," your job is not done. It's time to put on the editor hat and get back to work.
Words and expressions to omit (also a good time to be more specific):
Really, very: It was really cold. How about: “It was 14 degrees below.”
He was very angry. How about explaining how angry he was. “He was furious.”
That: If the sentence works without it, delete it.
Then: “I kissed him, then I blushed.” Rather: “I kissed him and blushed.”
Just: I despise this useless word. “He was just 14 years old.” Rather: “He was 14 years old.” (This says it all, really!)
“It was just starting to rain.” Rather: “It began to rain.”
Think of all those adjectives you could omit, that are really, just not needed:
Completely Absolutely Basically Virtually
How about those unneeded phrases:
As well as…
In addition to…
In the meantime…
The fact of the matter is...
Problem words to look for, excerpted from Grammar Girl’s Quick and Dirty Tips for Better Writing:
a lot/alot
affect/effect
can/may
further/farther
good/well
i.e./e.g.
into/in to
it’s/its
lay/lie
less/fewer
that/who
their/they’re/there
then/than
who/whom
your/you’re