You're afraid because you're thinking about the end, not about what you're doing.
It is in the contrast of light and dark that design happens.
It's not what you paint. It's how you paint it. You don't have to paint elaborate things. Paint simple things as beautifully as you can.
I switched to painting with my left hand to be in better company.
If it's all wrong, it's all right.
You can't get it right, until you make it wrong.