Going to make a really quick reply, since I'm still learning this stuff myself. More skilled artists will be along eventually.



References: Use references for everything you do, unless you're already a very good artist. The pants, the hair, the face, the shirt. Google images is your friend. Imitate reality.
Hue: Brighter objects that catch light are often warmer (more towards yellow), and darker objects in the shadow are often colder (more towards blue)
Contrast: Almost no one uses enough contrast when they're starting out with pixel art. Exaggerate, push the limit to what you feel is appropriate.
Light source: Decide where the light is coming from and be diligent in applying shadows that match the light source. This also affects the reference images you're using.
Shapes: Try to divide complex objects (like legs) into simpler objects (like cylinders) when applying light and shadow. It makes it easier to visualize how to apply light and shadow.
References: Did I mention you need to be looking at references?

Also, check this out:
http://www.pixeljoint.com/forum/forum_posts.asp?TID=11299

Thank you man. That is a huge help for me. I will defiantly use a lot more references now, I'm wondering what your process is for finding references is? Do you just do a google image search?

Again, I can't thank you enough

Hey. A few years ago I got into pixel art and created a few pieces of simple, crude pixel art, with lame stuff like mixed resolutions and such. I basically just started working, never bothering to look up any tutorials or guides, and trust me, it shows, as you can see below.
Spoiler


 I've recently gotten back into it, and I've spent a bit of time looking over the usual starters guides and stuff like that. I've only drawn the rough outline of the piece I'm working on, but I'm already concerned about its size and resolution. I'm worried I might of bitten off more than I can chew.



Ignoring the lame hand and lack of fully lining out,(I really just want to ensure I have the right size and resolution first before I tidy up ) this is what I have so far. And from my concerns I tried to create a smaller image, here:

I'm wondering if you guys could give me any general advice on what to go for here. As I am pretty lost myself.

TL:DR I used to make rather lame pixel art on the fly without any consideration to size, resolution ect. I now want to make more visually appealing art, and am so out of my depth, that I desperately need advice on what I should do with my outline