Thanks :3 And I have handful of hints:

One - are you using option to rotate picture? helps when you need to draw stuff at angle
Two - using stabilizer, dunno if you use it but can help making your lines smooth
Three - on how many layers are you working? It's good to sometimes have separate layers for groups of colors.

Oh and you gotta learn cleaning after yourself :3

no prob,
-_- i rotate the picture alright,stabilizer?what is that? 2 layers
well,this is my first time tracing pictures, i can't be perfect that fast =|

It's alright.

Sai has stabilizer (can be called differently) setting. It's on top - most rightmost thing set to 0 I would presume. try 10, then you can try slow setting - do some quick moves, slower ones etc.

ohh.....thanks for the tips again amdor ^^
and again i'm sorry for the crappy art :p

*hugs* it's not crappy ^_^ you just need more practice and checking if you didn't miss something - cleaning up ^_^. Working on tablet is different to traditional work (in which you're awesome) and you need getting used to it.

Remember than even when you are tracing your art you need to focus less on trying to re-make it perfectly and more on checking is everything looking good.

Don't be afraid to experiment - try out blur, check tutorials. You'll get better in no time ^_^