Artist, any tip?

Hey, so Im writting this so I can improve my art. I haven't draw for a year now im really struggling to improve I'v already tried tutorials or art  guides yet I can't do them properly. 

I want to improve my art so i can make a little money out of it, Im 16 years old, I have one more year of highschool till i have to go to university, till that time arrives I really want to save money. The thing is that my parents won't allow me to work or do anything about money. I know i dont have to worry about this but im getting tired of relying so much on my parents... 

So any experiencied artist or that knows how to help me, plz comment this blog. It really helps me any type of tip.

Im pretty much good with colors so my issues with art is: anatomy and backgrounds!! I would also like to what is the best that sells in art community

Thanks for reading this!!!(English is NOT my first language, sorry for any mistake)