The hair is good. You did a nice job there.
I meant the hair on the face like the eyebrows mustache and goatee and where the hair meets the face on the sides only.
I think using a little bit of the lighter browns would smooth things out.
Again, its a nice portrait.
Thank you very much,Jalonso!I'm very glad to had some good advices so fast. (always loved PJ)
about the hair,i was really lost about what to do,I'm playing with this style for a few days.I think i will reamke all the hair using a new style I'm working on,I'll submit one work i recently did this way,i'd love to get hints on this new one too because it's important to me achieve the niciest level possible because i'm deppending on it to make money actually 
I Will make the collar the way you said (i fell shame about it hahaha),and sorry if i did too many mistakes,english it's not my first language 
This is a very nice, clean and attractive avvy.
Technically however it really could have been way better had you used the 2 lighter hair colors to smooth and unband where the darkest brown meets fleshtones.
The odd lighter color in the neck is just wierd :/
The black lineart in the collar is jaggier than need be,
Top line would look better as 11122522111 and bottom 3211123454321123
Oh Yes!Now i see what you mean.
Let see if i can explain with my english hehe,I'm not working with any kind of smoothing or anti aliasing
because those portraits are meant to be used on mugs and frames(i sell then with the portrait on it)
so i put it in a zoom of 500% and smooth and aa on this size don't look very nice,and my clients don't uderstand abour pixel art and they think smooth and aa are "messed".
But now that i see your example i'm in love with it *-*