/ic/ - Artwork/Critique

Always wanted to learn how to draw and finally got around to finish the Picasso's Igor Stravinsky upside down practice and I have a couple of questions

when you want to start drawing, where do you start?
where do you continue from there?
when do you "conclude" that part, break off, and start drawing other part
how do you connect to other parts you finished without gross misalignment

picture posted is the second draft

for my first draft, I merely used ms paint and just started drawing from the top left corner. It did not take long until I realise it is grossly out of proportion
did not finish the first draft. I went from "his left trouser" to "his left armrest" when I realise its not gonna work

For this draft I started from "his left eye glasses" to his hair, before going back to his "left eye glasses" down to his mouth, down to his tie
at some point, I went back to finish his right eye, before finishing up the tie, and back up his right ear and finished his head
it is at this point, to my unlearned observation, tells me that to try and minimise misalignment, focus on places with details?
from what I can see of this upside down drawing, the details are in his head, and his hands?

I then proceeded to draw his lapel in line with his tie, down to his hand
this time, however, I went down his right lapel before his left
did not finish the left lapel, started going into the hands and fingers until I finished it do I then go back and finish "his left side of the coat"
even without flipping over, I can feel the connection from "his left arm" to "his left hand" is really bad

connected "his left sleeve" to "his coat" before going down the arm rest down to the left side of his trousers
from there finished the rest of the drawing, and end with a few touch up due to forgetting to draw that part