>>1699017>>1699029Basically what this anon said. You need to think logically how lines would actually form. You know that the arm line is supposed to go into the shirt, so the shirt line has to be above the arm line. The same applies to the hand. For instance, that large arc on the left side should not just be a line that doesn't connect to any fingers. It should be the main outer finger. The line below should just be for a crease for the palm of the hand.
You also should use the advantage of drawing through objects as one line, in order to keep thickness similar. You can then either cut out the parts that are supposed to be hidden, or making a clipping mask. It will help a lot in the long run.