@Reytuerto
Nice start when it comes to contours etc.
But there is one thing it lacks: shading - under the wings and horizontal stabilizers, as well as shading showing the round shape of fuselage.
(Upon closer inspection I noticed that there's indeed a 1-pixel thick "lighter" stripe along the upper contour of fuselage, but the shade difference is almost unnoticeable - make it more pronounced and bit wider, like 2-pixels, plus add a darker shade along the bottom contour)