Creating and using brushes
What are brushes? How are they used? How do you make your own brushes? How to convert
stamps (image packs) into brushes?
After reading this tutorial, these questions should be cleared :)
You can find my collection of Photoshop brushes and image packs here.
Brush usage
Brushes are in fact imitations of the real-life brushes. The idea is to be able to draw with them the same way we do in traditional art (or even better), so each software (in our case Adobe Photoshop) tends to offer many different brush styles.
Photoshop has a fine set of default brushes. Beside the ordinary circular you probably use often,
there are sets of alternative shapes, such as grids, sponges, stars... To find more brushes, you
must use the brush inspector. You can open it by clicking on the tab Brushes in
the upper right corner of your workspace.
Unless you have the Brush tool 
selected, you won't be able to use the inspector options, so go and select the Brush tool
(by mouse or press B on your keyboard).
We can now see a lot of different brushes, like Spatter, Chalk, Star, Scattered Maple Leaves... But, those are not all brushes avilable to us. Click on the small black arrow next to the word Brushes: this will open a large menu, and on its bottom there is a list of brush sets avilable. Select, for example, Assorted Brushes. You will be asked if you want to replace the current brush set, or just append this brush set to the existing list. Select whatever you wish.
Now, try out some of the brushes. You can change their size and settings (menu on the left of the brush list). Just play with the settings a bit an see what result you get.
Note that all sets listed in the menu are (most probably) located in the folder
C:\Program Files\Adobe\Photoshop X.X\Presets\Brushes (X.X being the program version,
mine is 7.0). If you have downloaded a set to your disk, but it's not in this folder, Photoshop won't load them
in the panel automatically. You can either move them to this folder, or load them manually each time you
wish to use them by choosing Brushes > Load Brushes....
Creating custom brushes
Before you make your own brush set, you must delete all the old brushes from the brush inspector.
It won't delete the brush set from the disk, only from the list of currently used brushes.
You can always bring them back by loading them.
Select one of the brushes and right-click > Delete > OK. Repeat for each brush until
the list is cleared.
Step 1: Pick an image
It can be a drawing, a photo, whatever you find convenient. The idea is to extract a part that you like to use on your own blends. Make sure you have permission for use of a certain image if it's not made by you.
Step 2: Desaturate and Contrast
Your brushes must be black and white. So if you're using a colored image, first go to: Image > Adjustments > Desaturate (or hit Shift+Ctrl+U). This will turn your image to grayscale. Then, go to Image > Adjustments > Brightness/Contrast... and change the settings while you look at the image. There should be as less gray as possible, as much black and white as possible (except if you're going for the misty look) - try to make it clean and recognizable.
Step 3: Extract brush
Pick Polygonal Lasso Tool
and select part of the image you wish to use as brush.
Go to: Edit > Define brush... It will pop up a window showing properties of your new brush. Enter name and click OK.
Check out the brush inspector and you will find the brush there. Yay! You made yourself your first brush! :D Try it!
Step 4: Save brush set
When there are more brushes on the list you would like to keep, save them as a brush library (or set). Choose Brushes > Save brushes..., enter name, save and you're done :)
