change frame size to max height and width, then adjust the width to be your reference proportions. once you've done that, it ultra-minisizes the 1pt pen compared to the high resolution canvas. then all of your details wont be blurred and you can make really small changes. You can also use 1% - 5% opacity black or white to shade things over and over and lay shadows in spots your brain accurately shades instead of using trial and error linework