When in Doubt, Expand it Out!

I have been teaching exponent rules the past couple of weeks and that is my mantra.  I repeat it over and over, encouraging students to understand the rules.  They are often in such a rush to use a "shortcut" exponent rule, that they try to apply it before they actually understand how, why, and in what situations it works.  

Now, don't misunderstand, I actually DO want my students to learn the exponent rules and use them.  I just want them to fully understand WHY they work first.

What do YOU repeat to YOUR students over and over?