RE: Pixel Art Weekly Contest Entry- Magical Forest

Deviantart and Pinterest have a lot. These are some of the better ones I could find right now:
https://www.pinterest.com/pin/557813103817334131/
http://vanmall.deviantart.com/gallery/10198081/Pixel-Art-Tutorial-Series
http://gasara.deviantart.com/art/Pixel-Art-Tutorial-Basics-for-Beginners-356743783
There are many styles in pixel art.
I began learning by trying to draw basic items for minecraft- apples, tools like sword, shovels, potions . Start with 8x8, 16x16 or 32x32 to learn faster. Afterward you can adjust size to your own preference. Out of those 3 sizes 16x16 is probably easiest.
After small items you can try bigger ones like trees and stones. Try working with only 1 base color, 1 lighter version of base color for light areas and 1 darker for dark. Try pixel dithering to find your favorite style. If you feel extra motivated enough try making a simple self portrait, like a game character. :D
Also there is a free version of Pyxel Edit, definitely try it (I use the bought one for character animation).
Good luck!