This is a departure from my usual writing assignments, which give you a theme to help get your creative juices flowing. This is an editing/proofing assignment which everyone who writes needs to do.
Take something you’ve written—fiction, non-fiction, term paper, blog post, etc.—and Find (in Word, this is Ctl+f) every occurrence of the word “that.” Read the sentence containing the word and do one of three things:
1) Remove it (re-read the sentence to make sure it still works);
2) Replace it with “which;”
3) Leave it alone.
I’ll give you a hint: you should do #1 and 2 much more often than #3.
Overuse of the word “that” is something that I’ve been very guilty of, and as I edit my book, I’ve been taking it out left and right. And where I don’t take it out, it usually needs to be replaced by “which,” which is more proper, grammatically-speaking. There are actually few instances where “that” is needed and nothing else will do.
In fact, I’m so attuned to it now, as I read other people’s work, I find myself mentally deleting it or replacing it with “which.”
Oh, and something else I’ve noticed, as I’ve been reading other people’s books, is that the comma is falling out of fashion. This has been going on for the past 100 years or so, but it’s getting worse. In fact, it’s getting to the point that sentences don’t make sense anymore without them. Better to have too many commas than too few, so check those as you edit your work too.
Personally, I don’t have a problem knowing when to put commas, but I know some people do. One thing I do, as I write, is I hear the sentence in my head (you can also speak it aloud, if you need to); everywhere you naturally pause in speech, that’s where you need a comma. Commas = pauses. If the written word was music, they would be quarter rests.
Keri M. Peardon 
Great little post.
I was a bit miffed to hear the comma had become a fashion victim.