I think everyone has covered most of the serious points (good work on the lighting etc) so that leaves the picky stuff that everyone points out to me that I've missed.
Unlike Dan I assumed that she wasn't high but she does looked b.o.r.e.d. (get on with it Mother, I want to get back to snapchat!).
Do you talk as you shoot? Talk to your subject, joke, encourage, DIRECT them towards the expression you want and when they hit it or even get close ENTHUSE and tell them how fantastic they look. That was hard for me to learn to do but it is SO worth the effort because it works wonders and you see your subject start to glow and perform for the camera.
Shoulders. The hair over her right shoulder in this case prevents football shoulders but it's good practice to have your female subjects stand at an angle of about 35 to 45 degrees and turn their heads towards the camera.
Before you shoot a series of shots look at your subject and check for things that are out of place. She may have been perfect when she entered the studio or for the previous batch of shots but check again. Somehow that necklace got skewed around and it's distracting.
This is all stuff I learned from some of the stalwarts here to whom I owe what small skill I have gained over the last few years. It feels odd to be passing it on.
I will add in fairness that young teens (especially your own kids) who have their arms twisted to model for you are notoriously difficult subjects. No matter how attractive they are they tend to lack confidence. I personally much prefer to shoot women over 25, or even better, women over 45.
P.S. All my studio strobes are stuff off Ebay or Amazon and the only item that cost more than about £60 is my new vinyl wall mounted backdrop. If you can afford it brand names are fine but you don't have to break the bank and reduce your family to penury

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