Updated the second one

I really like the rich colors of the first one. A very nice use of lighting. Perhaps you could unify the values some more in the areas where you don't want too much attention to not distract from the focus of your image? For the second one it seems like the colors are in relatively the same range value-wise. You could change the image to grayscale to check. Value pulls a lot of weight when it comes to color. Even if the saturation or hue doesn't quite fit, if the values are right, you'll still have a pretty good result. Also the green and blue of the clothes are very vibrant and compete with each other.

I struggle with value a lot myself. one thing that I've found really helps is to break down the biggest value shapes and use only three to four values (shadow, mid-tone and light). as you progress through the painting, you can start diverging from your basic value preset. If you struggle with colour, I suggest you first stick to monochrome paintings.