Make sure they're nicely firm and green. They're fairly cheap too, and can be bought at any supermarket. Make sure there's no yellow spots or significant detachment of leaves.
I used to dislike them at first because I didn't know how to make them taste good, until I discovered that they REALLY...
At first I was one of those people who was like "organic food? Pfft waste of money!" thinking that the pesticide issue isn't such a big deal, but that was before I was health conscious. Now I try my best to buy mostly organic, especially after when I discovered a shocking truth about pesticides...