You have some nice characters going i think, but your anatomy is a bit off.
Just like the guy previously pointed out, the left arm looks like popeye, versus the right looks more like a girls arm.
When you draw characters do yourself a favour and have some reference photos up, it helps a great deal!
Or download this app called pose tool 3d by alientthink, it's great if you want to do a specific pose, you can change body type from fat to thin skinny muscular, women/man, etc.
But you have a lovely drawing style otherwise, you just need to get that anatomy right! What you also need to get right (i'm just guessing here).
But are you using a drawing tablet cintiq or something of that nature? I think it or the screens you are using needs calibration in your graphic cards drivers. Cause it seems like you are not seeing the colors correctly on the first drawing of the "black woman". If you use windows there is Color calibration in screen settings where you go thru alot of tests to find the right settings. It can help A GREAT DEAL in matchning darker colors. Otherwise you draw blindly, in worst case! I did, for several weeks, until i realised it was the screen itself that was not calibrated correctly. Obviously there are many forms of calibration, and getting the colours/light right on the screen is essential!
Good Luck!