this first one is really solid!! a couple of things I'd reccomend is watching the proportions of the face. Something I've noticed is that artists (even professionals tbh) often times stretch eyes too wide horizontally. Make sure not to elongate them, especially when at a 3/4 view. It's really easy to think "oh this eye is going to be wider than the foreshortened eye" but then they get way too long. It happens. I drew in a little chart to show basic facial proportions (although you've probably seen this before). It gets skewed with the angle, but remember that the lips end halfway across from the eye (think about where the pupil is).
Additionally, since this 3/4 is more drastic than the usual angle, the nose is going to be a bit more foreshortened and pulled over to the side. Remember not to completely lose the nostril that's turned in. Coloring/shading is the best way to denote this but we're working with a sketch so it's not a huge deal.
When drawing upturned eyebrows, just adjust the shape of the brow, don't completely move it up on the head. If you wiggle your eyebrows you'll see that they don't actually move up/down that much. They kind of got drawn up diagonally, but the shape of the face follows a curve around.
When drawing the lips at the edge of the face, remember there is a cheek behind! I drew this in orange. 3/4 lips are tricky because they break the edge of the face, but that edge is very important in grounding the features!
Since she's looking over the shoulder, its important to think about the neck. Her braid covers it, but the skin of the neck is going to twist around and get pulled as she turns. Additionally, there is a muscle there called the sternocleidomastoid! It starts just below the ear and ends at the collar bone. Theres one on each side of the neck, making a little V shape. I personally think this is one of the more important muscles in portraiture just because it really helps define the neck, and makes it look less like a simple rectangle that holds up the head.
The last thing I want to talk about is the shoulder. It kind of gets lost in her hair fabruc, and what I outlined in yellow is what I *think* you were defining as the shoulder but I'm not 100% sure. The tilt of her shoulders drawn in the original is very close to a profile view, but the front of the body isn't drawn in. I drew in the shoulder and deltoid, but you could also leave the shoulder as is and give some indication of the chest.
Hope this was helpful!! I'll get to the second later this evening, it's been a hectic day!