May 18 Sketch

If you've done the tutorial, i suggest you practice more the spinal column line sketching.

It can be a straight line, a smooth curved or a half of circumference. This is the first main point to capture the essence of the pose. Along with it, you'll sketch lines for legs and arms

Then you can draw the 3 circles: Head, chest and pelvic area. These 3 can rotate almost on their own (try to imagine those olympic gymnasts, am i right? :) )

Also, don't be afraid to put more pencil/pen pressure. This first moment is to practice contour and basic human gesture. But i suggest you try to use a 2H pencil for lines and circles and 2B pencil for contour

And since you've done within 30s each gesture, i think its pretty good! Practice everyday and challenge yourself with different time limits and many different poses.

Those are really good renditions of the portraits. They do come off a bit stiff though, adding a solid line of action to highlight the center of mass will help the poses to have less stiffness.