Never underestimate the power of complimenting a musician.
One of the biggest fears is that we’ll perform with all we have and yet nobody will respond, nobody will be moved, nobody will care. We might as well have not have even played anything.
Musicians want to be remarkable: being worth remarked about, even if that means constructive criticism. At least then you would have thought that the musician was worth helping and nudging in the right direction.
Like any artist, musicians want what they do to matter. Every compliment, comment, and constructive criticism matters to a musician. Please don’t forget that.