Chaos Project

Hey. I'm working on a game that includes a 'purple forest', you know, like a mythical, magical one?
I made my own tileset, but at the same time, I don't like how it turned out. I know there are hundreds of things wrong with it,
like for instance, it has an inconsistant cliff tile, as in: You can only make it one way, and you can't bend it or be very creative with it.
Here's what I have so far:

The only thing I really like about this is the ground tile. =.='
I just need some help with how to make your own tilesets; or a really good tutorial on working with pixels. I'm really ultimately aiming
for my tilesets to look as original as the ones in Aveyond II: Ean's Quest. (I know I probably won't get that far, but it's just a goal).
Can anyone help me with this tileset?: