Hi GriGri
Nice studio portraitures on yr first attempts. Well I'm not sure if yr school studio has enuff studio strobes or not, but for pure white backdrop, you will need another 2 sets of strobes for the backlight, hitting the backdrop with light ratio 2:1, which is 1 stop more than the main light. For example, yr main light reading is f/8 aperture on the model, then yr backlight reading should be f/11, taking reading from the left side of the backdrop, center and then the right side, to attain a constant accurate reading. This type of lighting setup is usually used for glamour & fashion studio shoots. Well you can always have more control on what types of lighting setup you want to achieve certain results.
OK coming to the flower, tattoo and necklace, I find it distracting too. They do not match with the model's outfit. The more stuff you input on the model the more you have to worry abt details, well unless you are shooting based on a theme e.g. romanticism, you'll need more props & stuff. Keep things simple for the start and concentrate more on the model poses (preferably head & shoulders first b4 going into half-body & full-body) and playing around with different lightings.
The model is photogenic and has a great sweet smile. Based on the half body shot you posted, we can see that the model has a smaller left eye than the right eye and a bigger right jaw. You did a great job on positioning the model's eyes & face for #1 & 4. By turning & tilting her head to her right side, the perspective of her right eye is further from the camera which resulted in a nice balance in size with her left eye. Same goes to her jaws. :thumbsup: Personally I always avoid shooting directly face straight unless the model has a better bone structures.
Above are my 2-cents worth of comments. Hope it helps. Keep up the good work. Cheers!