Using patterns with brushes and for grunge:
First thing - this section assumes you understand the use of brushes in photoshop 7.
OK, With photoshop 7 we have some great ways of combining patterns into our
brush life. I have chosen a very basic brush, the 45 pixel diameter soft round
brush:
I now go to the brush options and define the following settings:
And also make sure the "noise" option is checked, too.
The following image is the final result and the differences you see between
each section is due to me changing brush blending modes:
And here's a quick take on grunge and patterns, I took the above image and
ran the threshold option on it ( 'image' menu => 'adjustments' => 'threshold'):
And this is the result:
Basically the choices to play are endless. I'm just offering you a few basic tips which you can then enhance to your own creative benefit.