okay, here's some tips i hope will help you. first off, use cleaner scans/linearts. this looks too messy for my tastes, and some of the lines are jagged. plus, its a little too "black", if you know what i mean.
secondly, the noses and the lips, especially in the upper left panel, are way too defined. look at real life pictures or the works of other good artists, and try to find a better way of doing these areas.
thirdly, clothing folds are a great way to give depth to a picture, but the two bottom panels have waaaay too many, especially sasuke's arm in the right one.
also, you could work more on the skin areas, but i think the quality of the lineart is at some fault here, cuz there is way too much black to see what is really going on.
lastly, look at tutorials, other ppl's work, etc, and try to learn as many of the good aspects you find as possible!
keep it up!