Industry standard for creating textures is through 3d modeling apps or sculpting apps and photshop. Its not very hard to make a good texture trust me people tend to inflate it much more then it needs to be.
*you can skip the 3d modeling portion and just fake Ambient occlusion if you read on, though sometimes it is essential to model things such as a sci-fi wall since there is no photo of one for you to use.
Lets say you want to make bricks, make bricks in your 3d modeling app this is best by tracing a reference image in your modeling app so you can use the photo base for your diffuse later. Once you have modeled your bricks you can call it done at this point and bake out the ambient occlusion, this is the texture pass for lighting/shadow and it is great for making textures. So if you traced the reference image take your AO map into photoshop and set it above the background layer of your photobase. Set the blend mode for your AO map to “multiply” and then you will immedietly notice the lighting information gets pieces into it, and any sculpting details are added as well, such as stucco, rough plaster, cracks and the like.
Now for the second detail pass!
duplicate your photobase layer, and then run the nvidia normal map filter through it at a scale that looks between smooth and detailed, not too grainy not too blurred. Then go to the image adjustments and apply the black and white filter, then go into the levels adjustment afterwards drag the first two arrow sliders towards the right, and then the arrow slider on the far left towards the left, you will notice your image goes black, and most of the exposed areas become white. This is great for the second detail pass. Finally merge this black and white image into its own layer and once more, set it to multiply. Hit ctrl+I to invert your image and emboss the exposed areas faking an ambient occlusion pass. You can now merge this image into the base diffuse, obviously you notice your image once more is probably pretty dark of course this is VERY easy to fix. Go to image>Adjustments>Brightness/Contrast and boost your brightness until it looks perfect again. After this if you are happy you can call it done right here.
Scratches
Wide Scratches can be put in place here if you wish to proceed onward, brown/white/gray/yellow/flesh tone works great for wide highlight strokes, use gray or black for cracks keep in mind that you want these in separate layers to keep changes easy to update.
Now for 3rd Teir Details
3rd Teir Details are the final pass of character to your texture, these are done with base photos, for example rust concrete, fungus, and such things are added with overlay and multiply blendmodes, at VERY low percents such as 5-20%. Decals are great for this stage as well, and doing final tweaking with the curves adjustements can help bring out that final pass of shadowing that won’t look odd in a game as compared to a straight photo. Dirt works great at this stage as well.
-Scratches and highlights!
You are now in a position to add final color passes with a pen tablet of small scratches, and definition of highlights once painted on set an appropriate blend mode and/or opacity. Also at the bottom left of the layers box you can add the “fx” to your paints such as bevel and emboss to add a bit more depth to a highlight.
Some Notes, you can just as easily bring in separate Ao maps into the texture, for example do the AO faking on a concrete texture, and then just take the AO not the color and multiply it onto a rock texture or vise versa. Or take a brick AO bake and multiply it onto a concrete or stucco for some concrete bricks mix and match as much as you like. Or maybe you have a cliff you like but the color does not suit, so find a base stone with nice color, and take the cliff with all the cracks you like and multiply it onto the base stone color map, that way it appears as though the cliff was made of that stone material to begin with.
To have a similar color palate in a game for good composition use the image>adjustments>match color feature in photshop, for example keep your wood textures the same so it appears as though it from the same type of tree that would seem more logical to be found in the region of your game. Use it more sparingly so that it does not appear you have a monochromatic game as that would look bland.