From your current drawings, I only have one advice for you, an advice I gave to thanqol back then too.

When you draw/sketch, don't use multiple short lines. It's one of the worst thing you could do while drawing. Basically it will make your drawings looks 'furry.'

Draw longer lines instead. Don't feel defeated when the lines aren't straight or go to where you want them to, just draw another line on top of them. Take a note on good sketches example, you might notice that they indeed draw multiple lines over and over to make shapes, but the lines are long and 'shape-making'.