Re: Vibrato
I didn't used to think much about vibrato until I listened to a recording of my singing played a double speed. That made my vibrato VERY obvious & easier to analyze.

I was starting a note with vibrato, then that tapered into a more pure tone as the note was sustained. I realized I was not "hitting" the note correctly right at first, and used vibrato like a hunting dog to eventually sniff out the true pitch.

After realizing that, I made a point of practicing hitting the correct pitch right off, and only bringing in vibrato when I want to on sustained notes rather than using it as a crutch for sloppy singing.

Maybe I'm the only person thus afflicted, but I thought I'd share.