Yes..background because it's dark still ok.I can see shadow from flash.Try using a piece of tissue or tracing paper wrap around flash to diffuse the light.
The hands not posed right..left hand fingers are splayed with 4th. Finger in pocket, close them together.Karate chop look better than claw fingers. Right hand looks cutoff. Should have gone for 3/4 body shot than half. Mujer hermosa!
How you frame the shot for a portrait makes a diffrtence.A tighter frame reduces distracting details, it guides the eye to the model rather than wondering around the frame.Do you think it is more efective, have a look.
If this is a recent effort..nice but the left arm n hand is hidden.Managing her hair I suppose. A better pose I think will be her left hand managing her hair out in front..gives her hand something to do and looks more natural. Her facial expression could be better with a playful smile. Her hair is alright , use it to accentuate her figure creatively. Can ask her for suggestions, get her involved in the process she will have more fun and her expression look interesting. Looking more like a pro shot. Keep it up.
You should direct or give instructions to model or else she does not have any idea what your photographic vision is.
By straightening her left arm she looks tensed although her facial expression is good. That is why you need to relax her by small talk..getting her to relax her shoulders goes a long way.One way of relaxing her is asking her to perform physical movements..
Walking, turning, dancing,even jumping up and down. Warming up is the key. Hair management
Has improved. Keep it up.
Ps same with moving other parts of the limbs.