The most common, DEAR-GOD-PLEASE-MAKE-IT-STOP grammatical errors you can fix in two shakes of a lamb’s tail:

1.) YOUR & YOU’RE

Ask yourself: does someone own what you’re describing?  Then it’s a ‘your’:

your books, your shoes, your love, your thankfulness, your dirty laundry, your umbrella

If no one owns what you’re describing and the words ‘you are’ could replace it in a sentence, it’s a ‘you’re’ you’ll be needing:

you’re awesome, you’re a pal, you’re going to the fair, you’re silly, you’re super

Again: ‘your’ indicates possession, ‘you’re’ is a contraction standing for ‘you are.’

2.) THEIR & THEY’RE

Just like our previous example, ‘their’ indicates possession:

their shoes, their party, their website, their company, their toilet paper

If no one owns what you’re describing, ‘they’re’ stands in for ‘they are’:

they’re nifty, they’re mean, they’re quite a pair

Again: ‘their’ indicates possession, ‘they’re’ is a contraction standing in for ‘they are.’

I saw your eyes glazing over, so I’ll stop there for now.  But, if your grammatical brain is suddenly wishing for more ways to self-correct, I would hit up Grammar Girl’s Quick and Dirty Tips. Grammar Girl rocks.

Want to read it on the blog? GRAMMAR COUNTS, TOO.