Steve’s advice is spot on, and it sounds like you’re already paying attention to that. See if you can get someone to take a few pics of you at full draw. Even though I fully believed that I was keeping my elbow flat at full draw, the pics made it clear that I wasn’t, and I needed to work on it more. Beyond that, I think that seeing what your form actually looks like occasionally is a good thing.
As far as ‘plucking’ goes, I can only offer what solves the plucking issue for me – a second anchor point upon release. As the string leaves my fingers, my hand moves straight back, never leaving contact with my cheek, until I hit my ear lobe. I see some exaggerated releases with the release hand flying all the way back to the shoulder, and whatnot, and 1) I don’t think there is really any need for the release hand to move that far backward, 2) in my opinion, it can increase the likelihood of the release hand straying from the same plane that the string is on, therefor causing some ‘plucking’ effect.
Jeff Kavanagh does a good job of explaining it in this video:
Also, I know its largely a personal preference thing, but I find that I get a noticeably smoother release with a tab than I do with a glove.