I remember seeing these on KG. Good start man. How old arre you?
My advice forr taking it to the next step:
1_ Hand writing. Remember drawings are about communication. If you have notes on there, which can really help the viewer, they should be readable and aestheticly pleasing.
2_ Proportions. Study shoes that you like, what about the shapes makes them better than other shoes? How do the details flow together? Study the relationships of the shapes.
3_ Drawing style. Study drawings you find successful. You wil often find variations in line weight, some way for the drawing to interact with the page via a ground plane, shadow, or vignette. Things like this.
Good work, keep it up man.