Hold on...
you mean SKETCHING the figure. Yeah, that's why I have some trouble coloring the hair.
By the way, Vlad, are mechanical pencils recommended, cuz I use that for all my draws.
When I say lineart, I mean the basic lines as a final piece. So no, I don't mean sketching the figure, since sketching isn't developed to a point where line art is pronounced or refined. Think of line art as a sketch thats fully developed, polished, and ready for coloring. Its like inked drawings. Thats a line art. It can either stay that way or be colored. If it's colored than the line art is the base from which to build upon. Pictures that are not refined, corrected, completed, or adjusted are sketches or doodles. A line art is art thats finished, or is ready for the next step (coloring).
As for hair, part of your problem may very well be that you're treating the hair in a sketchy mentality. You're not refining it enough that it's balanced or correct. Its just as is, just like the outlining on the figure, which is the main problem of this picture. Improving the basic structure of the piece before you move on to coloring it will help out alot.
Finally, when I draw traditionally (meaning not digitally and not on the computer), I use mechanical no. 2 pencils, myself. They're cheap, have the right width, they're disposable, and you can get alot of them.
Some people might tell you that you need professional pencils and this and that, but you don't, really. I use basic pencils like that for the line art itself, and then fancier things like prismacolor pencils/markers for the coloring. But for the drawing itself, a mech 2 is fine. Although, I should warn you that being able to make the best of a cheap tool is a talent that comes with experience, so I wouldn't recommend stocking up on mech 2 pencils and have you thinking you'll get the results you want. You may not, so I'd look into what fits for you. It works the same way, even more so, with high-end, pricey name brand stuff. Alot of people invest in that thinking it will somehow magically make their artwork better or make them draw better. It won't. Then they get pissed off and either throw the stuff away or never use it. Then its all just a big waste. The tools are just tools, the rest is up to the artist.