Hey ! if you struggle with that, i would recommend the firsts lessons of Drawabox (it's a website with free courses) Lesson 1 focuses on basics and line quality but more importantly, on Cylinders/boxes in perspective (If you really want to get a good grip on this subject, at the end of lesson 1, you'll have the 250 boxes challenge, super grindy, but as you can surely guess, you will DEFINITELY have a better understanding on all of this !)

Nice attempts, my criticism is that you should practice how to draw fluid lines, I recommend you watch how to hold your pencil video form Proko that will help you a lot. Second, you are focusing to much on the contour of the figure, you should only use “C” “S” “I” lines, if you do anything more complicated than that you are not thinking of gesture. Don’t complicate yourself, a gesture drawing should be simple. Don’t worry, you will get good with time, you won’t completely understand gesture only on this lesson, I started to understand it in the manikin drawing lesson. I will recommend you to dedicate only 2 weeks on each lesson, then move on to the next lesson. Even if you don’t completely understand it, the other lessons will help you. Don’t give up, tag me when you do your corrections. Btw. Here are some photos of my pencil exercises.