The sketches look good for a start and you are picking some challenging poses which is awesome. AND it looks like a lot were from real life reference and not just images, which is more challenging. For facial studies, at least in the beginning, try using a line to show eye level reference. It helps with those odd tilted/angled head shots and speeds up the sketching process. Eventually, you might not need to use the line. I still use the line.
Also, some more of the interesting angles (like the laying nude woman) came out great compared with some of your profile shots and here is why: the interesting poses FORCED you to break the drawing down into basic shapes, because the pose is unfamiliar. The familiar pose made you draw what you knew and not what you saw (i.e. I drew an eye, not the triangle with a convex curve like I actually saw.) Continue to draw and keep breaking down what you see into basic shapes. You can always add the details later.
I looked the dates on the drawings and see you do this often. I recommend this site for daily work. (Try using the convenient 30 minute trainer once a day) and your overall speed, line quality, and proportions will show good improvement. Try doing it daily though. It will be hard to find time but you can make time. Get that pencil mileage!
Good start though, and you have a nice amount for a first-time poster. Keep adding to it.
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