Thank you very much for the resources! I will read them through so I understand pixel art more. ^^
Thank you so much for all suggestion! I appreciate it and I will work hard on it. I will check all the tutorials. :)
Sorry but if you use shaders, filters and gradients then this is not pixel art anymore. You've just resulted in digital art mimicking the look of pixel art instead and this piece won't get admitted into the gallery.
I'm absolutely sure however that you can create pixel art though; judging by your artwork in your deviant art page, you definetely have the skill. All you need to do is redefine how you create your art while you do pixel art.
There are several tutorials in the forums. I'd highly suggest you read them and familiarize with how pixel art is created.
If you're going to recreate this piece, then I suggest you draw the top of the head as well.
I checked out your deviantArt and your work is breathtaking! I can forsee you doing amazing pixel art, keep it up!
Wow, you have an impresive portfolio!
Please check this tutorial and this one.
You obviously have a lot of talent, and I'm sure you can master the pixel art technic. There's a lot of limitations in pixel art, but being able to master the basics will improve vastly your skills in other technics.
Cant wait to see more from you 
I really like this work. But I think it is no pixel art so, you have not my vote.