Not Good, Better

I think you should never say that you’re good at something.

Good is an adjective that others use to describe us. In fact, most words used to describe people are too subjective to be valid. And they only apply to the person saying them.

Most of the time ‘good’ isn’t clear enough anyway and needs more of an explanation.

You can't know if you’re good. 
But, you can know if you’ve gotten better.