One of the things I've been trying to add to my singing is more vibrato, but I'm not sure what technique to use. Any help?
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Vibrato is something that will come naturally. Singing with a pure tone is generally more useful. Forcing vibrato is unhealthy.
yeah, when you get good technique, it will come naturally. focus on breathing properly etc.
To me, my voice has vibrato to it when all the other pieces are in place. When I have a solid, relaxed breath and clear tone in my voice, vibrato comes pretty easily. You can actually control it, but the adjustment feels very slight and there's a lot less effort going on then you might think.

yes, yes, and yes. ^

Could I get some more talent in the monitors, please?

I know it sounds crazy, but try to learn to inhale your voice. www.thebelcantotechnique.com

Chris is the king of relating music things to other objects in real life.
Furthermore, honestly, with singing, vibrato is one of those things that always sounds really terrible if someone without good fundamentals does it. It's like seeing someone who doesn't know how to walk try to sprint.