Teach yourself first
A fundemental rule before you try to teach anyone anything:
Learn how to do it properly yourself.
Yeah, you clearly understand the absolute bare minimum required to create manga, but that's not good enough kiddo.
Work on your feature-lines.
Those 'lines', as you put on the male neck are produced by the top of the sternum and Adam's apple.
Eyes need major work.
Hair too. Seriously, you draw absymal hair.