Theres no secret shortcut, just lots of drawing practice. You must be able to draw well to even begin, then you just need a lot of patience to draw a few hundred thousand pictures of the subject moving wherever you want
I just did this straightforward in about an entire day >< The blue for the wings was just so i could differentiate which limbs i was drawing.
I have some tutorials on Youtube on some of the principles of animation which might be worth a look
They're linked in my gallery's guides and tutorials folder or just search for me on youtube (same username).