mistakes and sins

I've been trying to learn to be less afraid of mistakes. My kids learned in school to say "Everyone makes mistakes." Mistakes are a good way to learn. I grew up feeling so desperately that I had to be a good girl, and I tend to feel I can't afford to do anything wrong. In parallel to mistakes one might at least argue that we shouldn't be so afraid of doing something wrong, so long as we learn from it. How do we learn to believe in forgiveness?