This may sound like an extreamly dumb question concerning colour and proper pallet usage.

Usually, I just pick a few colours *(16 or less)* that I like and use their gradients on the slide bar *(I'm using Graphics Gale)*, but, this dosen't seem like the "proper" way to do pixel art shading, and use of colour. 
My work comes out looking either oddly coloured, or just lacking a set theme. 

Is there a link that shows reference to typical pixel art pallets, or maybe a site that would help with some basic colour theory knowledge would be helpful too. ^0^  

*Siren