Texture Practice

[IrresponsibleFreelancer]

Howdy been a while since i did anything (not 9 years but whatever) ive been a bit of a lurker for the past little bit so i thought id try something new.  Normally im the type of person to do characters so i thought id try tiles a bit.  The tiles arent intended to go into a game and actually be tilable.  Theyre just practice.  I also couldnt find a good sidescroller dirt and grass tile for the life of me.  The first one is supposed to be earthy stone with grass, the second is mountainy jagged stone the third one is rough rocks that are kind round and the last one was supposed to be some kinda muscley brain type thing.  Critiques and tips would be greatly appreciated.

[trough]

These look good to me, but there is one thing which jumps out: the highlights look noisy.

Here I darkened the highlight color and tried to reduce the amount of single-pixel highlights.  For the dirt in the middle, I removed the highlights.  Maybe my edit makes the dirt look too dull, but I hope at least the brain edit is helpful.