Hey.
the first thing I'd see is the fact that you have lots on contrast. the more contrast you have on a tile set, the noisier it will get. (that rimed, so it's gotta be true)
I meen if you make each tile look really good and contrasting, then all the tiles will be contrasting thus making the tiled image to look flat. you gotta think of the tiles as pieces of a whole image.
my sugestion would be you first make an image, and then see what can be tiles, and go from there.
take care
Kaz
