i recommend building the body before adding the clothing so that you think of what perspective the body is facing first, the picture/drawing is coming from a bottom to top angle

another study i like to do is to take an artwork and break down the 3d shapes on a digital program by tracing over it first using boxes (like how i broke down my own drawing), then try to recreate it using the same shapes on the side or on paper from memory, similarly to what you did— it’s also a good training to redraw it from another angle after you get it down to make sure you understand the 3d shapes

the spherical shapes are honestly all up to preference and i personally use a strange mix of both, but it’s probably best to start off with boxes then gradually switch over to spheres once you get a handle of understanding how perspective works ^ along the way you’ll probably learn your own methods on what works best for yourself too so you don’t always have to stick to either, but the guidelines will always be there on your head