Hi! You posted that you were looking for crit on this piece, so I thought I'd take a little time to write one out! First - I like that you're using complimentary colors to set your character apart from the background. It shows some knowledge of color theory and that you're thinking about that when you make your art! I would definitely look into drawing human figures from real life before jumping into anime - I say this because I'm noticing a number of anatomical flaws in your character, like the shoulders being much to small for a man (could maybe be swung for a girl though). The character is also lacking a hip structure - even though men have smaller hips than women, they do have them! Drawing from life will help you to notice and correct these flaws in your anime drawings. ^^ So far as the posing of your character - I urge you to attempt to draw a full body (or at least most of the body, including at least one foot) at all times when you are not drawing a portrait! Especially for character art where we are all trying to get the gist of your character. Doing this will help you to better understand and develop stronger proportion and anatomy as an artist, and will also get you on your way to more dynamic posing of your characters. Lastly! I would take a look at how clothes and fabric in general fold and hang, the lines and places where you've defined folds in the shirt and jeans are not accounting for his body underneath the clothing, which is why they are looking very flat.
Overall great effort though! Good luck with your future stuff!
Despite what the other critique said, i really like this piece, all the lines on the face etc are where they should be, the hair looks really good, especially from a distance. the background is simple, but that draws the viewers eye to the character which is what is needed to make a good piece.
if anything i would suggest work on shading on brightly colored clothes. that is really the only thing in my opinion that lets it down!!
So a little practice and you will be there, i really like this piece and hope you keep up the good work!!!