If you're not using scissors to cut the parsley, use your fingers to hold it in a ball on your cutting board
Start chopping the parsley.
Hold the knife handle firmly and, with your other hand, press down on the top of the blade; then, cut with a rocking motion, like this.
Repeat this motion several times.
If you'd like to incorporate garlic into it, now is the time.
chop it a few more times