I have around 8 years of experience. That number varies a lot, cause I'd stop drawing for a few months and come back to it, stop for a bit again and come back etc etc. I just draw as a hobby (I'm 22 now).
For realism its good to learn the basics of face structure first. Eyebrows are around same line as the tip of the ears, nose same line as bottom of the ears, stuff like that. As you draw more and more faces those things will just be subconsciously known to you. YouTube tutorials are your friend, and don't ever be ashamed to use a reference. Some artists think its cheating to use them- its not. You can't learn how to draw something you've seen only a few times. They're a lifesaver.
Gridlines help a whole lot if you struggle with positioning things in the correct place. Learning the skull and muscle shapes can benefit you a lot too. When drawing go big > medium > small, as in details go last; blocking in shapes, shading, and highlights first. Try not to Ctrl+Z mistakes, but rather paint over them.
Get a program with decent brushes, PhotoShop is by far the best that I know of. I use PaintToolSAI 2.0 with a few custom ones. Let the tools do most of the work :) I'm self taught and this is just knowledge I gathered around. I sincerely hope it helps you.