You're afraid because you're thinking about the end, not about what you're doing.
You can't get it right, until you make it wrong.
The first thing you see is the last thing you do.
See it in terms of paint. We don't learn subject matter, we learn paint. The musician can play any score that is set before him.
It is in the contrast of light and dark that design happens.
If it's all wrong, it's all right.