there no variations to your shading work at all son. there r so many different shades of black and grey u need to learn, white high lighting here and there. it doesnt come overnight. i been tattooin 3 yrs and im just scratchin the surface of black and grey
try using mags and putting down a light grey wash base then shadding over the light base coat with your darker tones for a deeper depth in your black n grey work .. fester