Well, that really depends.
if you have the patience to put yourself through it, the fastest way to get good fast is mechanical studies. Random shapes, spheres, triangles, squares, putting all that in perspective grids to practice that, learning basic posing skeletons, drawing ACTUAL skeletons, going out and finding muscle charts and drawing THAT, and on and on. It's like building a tower out of clay by packing on more and more new skills and study, sometimes going back to the base to reinforce that so it doesn't all go pear-shaped
really it's all just getting that out of the way, but not everyone's able to buckle down and push that no matter how much they wanna git gud.
Instead, figure out what you enjoy drawing. Backgrounds? Characters? Props? focus in on that and spiral outwards.
(If this all seems vague it's because this is also a vague question haha, without seeing your work I can't really guide you much beyond this)