the first image is the same as the forth one, i drew them from reference and then shifted them on the reference to highlight mistakes so that it would be easier to analyse them

In that case very nicely done

Nice work
I think with the singer you can exaggerate the curve of the lumbar spine or line of action to make the pose more dynamic

oh okay, thank you for the tip, i'll try it.
today I tried marc's method, the one he used in the female proportion video, tracing it onto ten reference and using it to copy 5 reference (on the bottom of the canvas there are the copied ones and on top the traced). then i did 20 1' gesture drawing and kind of an anatomy practice from imagination.last one took me 30 min and i really can see how much i'm better than whan i started, even if it was only five days ago. Feel free to give feedback's, they really help

Looks like you have a good amount of skills already! I look forward to seeing your improvement!

Thank you very much, I'm trying my best to get as good as possible

today i did 20 1 minute gesture drawings , some studies of marc's method and 10 5 minute gesture drawings; i don't know if the method studies are easy to understand because i did them on paper since i wasn't at home, but i would still love feedbacks on this