In my own experience of myself and others, people fall down more often on sins of omission than sins of commission. That is, most of us can avoid kicking a puppy (sins of commission), but not as many of us are willing to, say, offer a hand to someone having trouble getting off the bus (sin of omission).

... I think sins of omission are a kind of trap, though, because there is an ocean of bad stuff out there, and we can't apply ourselves to all of it.