Hello, I will say that, while I cant afford acrylics, from a time or money stand point I did enjoy working with them is school... This is what I learned. When doing people you seem to have a nice grasp of the human figure, while a little distorted, try to use a mixture of colors, one as a base a darker tone, and a lighter that can be used for your highlights for the peice. This can be very helpful if you have a simple subject or little time. The more time the more improvement you will see but from what you do have concentrate not neccisarily super fine detail (or my spelling ) but getting some basic forms down. I will try to keep up with your sketch book and till then enjoy I will try to keep checking the sketch book to see how you do.
Hmm, I like your art. On the quick anatomy sketches, I'd say don't take more than a minute per. Try to get the basic form down in a few quick strokes. Atleast, that's how I see it. Form is important in gestures.
However, I really do advise doing some semi-detailed anatomy sketches that takea round 30 minutes.
So, your gestures seem to be improving. You say they are from ref? Either way, they seem kind of blocky, you seem to be loosening up, but curves are the way to go.
Anyway, on the crosshatching: not a bad first try. When crosshatching, try to keep the lines going with the form of the object - you wouldn't make straight lines on a ball, would you? Also, vary the length between them, not just the amount of lines crossing each other. The closer they are - the darker, but try not to get messy. Messy looks bad.
There are a bunch of tutorials for portraits, cross hatching, anatomy, etc. all over this place.