Those are pretty dope, did you use a pencil? Somethin I heard some pros say sketchin of a pic aint the best cause you cant really get a feel for the dimensions and stuff. But regardless really nice job!
RIP Mike Szabo aka my Godfather.
Nice drawings....you did say though to offer any advice so, here are a few things i would take in consideration.
The biggest thing is patience. I dont know how long it takes you to draw one of the kobe drawings you posted, but take quality over volume. I know its hard to be patient sometimes, but it pays off end the long run. What i mean by patience is for example, instead of quickly shading his face, take your time and try to get little details.
Another thing would be to get the right materials. Whatever suits you best. Getting quality pencils and pens/markers and quality paper can make a difference. Try a smooth paper. That way you have more control and you can add more detail.
Last thing i would say is, have a plan made out of what you are going to do before you draw it. Maybe make a little pre-sketch on a piece of paper. Its good to pre-plan so you can add things without hassle.