This tutorial is 9 steps and it has a difficulty level of Intermediate. This tutorial will show you how to make a grungy rust texture. The result is pictured below. All colors in this tutorial are in hex value.
Finished

     1. First, create a new document, I used a 300 by 300 pixel image, however you can use whatever size image you would like to use. All colors in this tutorial are in hexadecimal (hex) value. Now change your foreground color to 723800 and change your background color to 412100.

     2. Go to Filter > Render > Clouds, and new you should have something like the below image.
Step 2

     3. Go to Filter > Texture > Grain and use the below settings. Then you should have something like the below.
Intensity: 50
Contrast: 50
Grain Type: Speckle
Step 3

     4. Filter > Brushstrokes > Spatter and use the below settings. Then you should have something like the below.
Spray Radius: 25
Smoothness: 15
Step 4

     5. Filter > Artistic > Sponge and use the below settings. Then you should have something like the below.
Brush Size: 10
Definition: 20
Smoothness: 1
Step 5

     6. Filter > Brushstrokes > Spatter and use the below settings. Then you should have something like the below.
Spray Radius: 25
Smoothness: 15
Step 6

     7. Filter > Blur > Gaussian Blur and use the below settings. Then you should have something like the below.
Radius: 2.0 pixels
Step 7

     8. Edit > Fade Gaussian Blur and use the below settings. Then you should have something like the below.
Opactiy: 25%
Mode: Normal
Step 8

     9. Finally, go to Filter > Noise > Add Noise and use the below settings. Then you are finished and should have something like the below.
Ammount: 8%
Distribution: Gaussion
Monochromatic: Checked
Step 9