Number 1, 2 and 3 I didn't care for much. Technically they are pretty good, but they both look a bit stiff in their poses.
The two last ones are pretty good, but would be better if you cropped them a bit.
The fourth one is pretty good, there's just something I don't like about it... just not sure what.. The pose is good, she looks natural, all in all a good picture. I would have liked to see her right eye better though.
The fifth one: she's centered, and that's just boring, isn't it?
The last one: again her head is centered, and the big red thingy just attracts attention from what you're actually trying to show (her). I'd crop it so the red thingy was gone, and her head was in the upper right third.
I think you're doing good though, adding a off-camera flash is one of the best way to get variation to your portraits.
Next time think composition and see if you can get the flash lighting them from an angle, that way you get a bit more shadow in their face (the good kind) and thus more contrast, making the photo "pop" a bit more.
A good start is having the flash at approx 45 degree angle, and slightly above her (just take care with the shadows under the chin (make her raise it enough to avoid the heavy shadows)
Again I don't want to sound overly critical, I'm trying to do as the japanse do here!
(In japan, if you speak a few words of japanese they fall over themselves and compliment you on your japanese, but if you speak it pretty well, they start correcting your mistakes instead
)
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I has a flavor!
CC always welcome.
firt time out though with the flash 