I totally agree with @DMBrigman they have some great advice! I use a combination of both of these techniques when I draw. For especially difficult foreshortening I will use the box method in the bottom-right of that box tutorial: drawing something from the front flat, and then drawing the boxes in perspective and using that as a guide to where each part of the body will fall.
Just wanted to say though, your sketches look great! Just keep the techniques in mind and as you practice and draw more it will become second nature and you will find a rhythm that works for you.
Also, I STILL take photos of myself for reference when doing particularly difficult foreshortening, especially on hands. Selfies are great for this! Good luck 