I don't know how people have a hard time just copying an image..
As you can see, the shoulders are too high, he's missing half his neck, his ears are..
weird... and his jaw is too wide.
I'm sure you can find thousands of tutorials on how to draw Dragon Ball characters..
Nothing's wrong with drawing images you see as practice, but try to "level-up" to a
point where you can draw your own poses and forms of the characters.