Hi and welcome to the forum!
I'm going to focus on the woman because that felt the most challenging to
me (way out of my comfort zone!).
First off, I think you did a good job with the glass, pearls and hair. These have clear identifiable shapes in simple clusters, and a few well-used colors.
On the dress and skin you have used 4 and 3 shades, but they are very similar to each other, and quite hard to tell apart. Also, I'm a bit confused what her right hand and legs are really doing, as you can also see in my edit.
In said edit,
- tried to reduce dress and skin colors (3 and 2).
- tried to use larger shadows instead of lines to bring out volumes.
- tried to understand pose and anatomy
- changed to a more neutral background.

I'm not sure if this goes in an intended Sierra style, but it's what I can manage.