When drawing bodies, the thing that's helped me the most is practice.

I've been fortunate enough to be able to visit a figure drawing class where I draw with pencil on paper. There, we learn how to use our pencil to check proportions - you hold it vertically at arm length and then see how often the tip of the pencil fits in the torso, the legs... and then mark it on your paper, similarily to how it's done in the tutorial with the head as a reference point:

It's very difficult for me to find techniques that work digitally for me, though. Here are two practice drawings of the same figure I did with the help of the XPPen tutorial:

They are based on a 5min and a 3min digital pencil sketch. I laid down basic shapes first: An oval for the head, a body line, the shape of the pelvis and cylinders for the arms and legs. Then I went around the shapes while always looking at the reference to get proportions and the outline right. After 3 and 5mins respectively, I added colors. It's easier to do this in greyscale first to get the values right, but I wanted to experiment.

I still have a long way to go but it's been fun!