How to style this vest/waistcoat?

I picked up this lovely vintage piece from Danier. It has suede at the front and satin at the back, with a very deep V-cut. I’ll admit, I don’t quite have the confidence to wear it on its own—I don’t exactly have enough to fill it out, if you know what I mean.

I was thinking of layering a turtleneck underneath, but I’m not quite sure how to style it yet