just wanted to tell you of a simple way to make your textures seamless,
for this example, i will be using this picture of some rocks.
open photoshop and paste your image in a new canvas,
select the top left quarter of the image, crop it,
then resize it the half the final image size
(if i want mine to be 512X512 resize the cropped part to 256X256)
Now duplicate the layer, press
Ctrl+T to enter
free transform mode, grab the square on center left
and drag it to the right where it will snap.
combine the two layers (selct both and click
Ctrl+e)
and this time, in free transform, drag the top center to
the bottom of the canvas, it will snap again.
if it dosent work well, try the same from a different
corner, but if done right, the texture will work seamlessly.
Here is the final texture in game, it needs resizing, and its not very sutible, but you get the idea
