The best one comes after you line up five of the same color. It's often called the color bomb. It's a chocolate ball with sprinkles. Swipe it against any other candy, and it will shoot every other candy of that color into the netherworld. Poof.
You get five lives, five chances to fail. There are a few options to get more, including asking your Facebook friends (no, thanks), paying for more (no, thanks), or waiting. Wait 30 minutes and you get a new life.
I have not spent any money so far, tempted as I have been. You have to draw the line somewhere.
I play on my iPhone, though there are versions available for Android and Facebook. A Web version pits you against strangers online. I sometimes resort to that when I'm out of lives on the iPhone.