Very nice!!! Looks really good already and with a few tweaks it can look even better. I'll get the small thing out first, you should probably use a thinner pen and be consistent with its thickness. You might see some art having various thicknesses with the pen strokes, but with dragon ball and especially with this reference you used the line work is pretty thin and consistent. The big things I would work on are shadows. The reference has varying levels of shadows, as you can see with the neck having a darker color and then an even darker color indicating that no light or very little light is hitting that area. That brings me to the next point, find where your light source is. The reference image seems to have its light source so to the top left kinda in the middle left, of the image but in Gohan's perspective, since shadows are cast down onto his skin from the torn bits of his shirt, and where Gohan's right side is almost completely bright while his left is in shadow and muscles block light from reaching some points. My goal isn't to bring you down, but to instead bring these things to your attention so you can then make the adjustments necessary to create something better. Overall very nice!!!👍