You’ll need to fine-tune the new brush for best results. Select the Brush Tool and choose Window > Brush. Once the window appears, click Brush Presets. You’ll see your newly defined brush at the bottom of the list of thumbnails.

After you’ve made your tweaks in the Brush window, you must save the brush as a new preset. Click the tiny document icon at the bottom right of the Brush window to add a new brush preset, enter a descriptive name for the brush, and click OK. The revised brush will appear right beside the original brush.

Changes you make to this brush are not automatically saved. Any time you change a brush, you must save it as a new preset.

Adjust your brush
At the left side of the Brush window, you’ll see a list of brush options. The options you enable will vary greatly with the type of brush you’re building. If you’re working on a brush that’s shaped like a wheat stalk, for example, you’ll be concerned with Shape Dynamics, Color Dynamics, and Scattering. At the bottom of the Brush window, you’ll see a preview of your current brush. Every change you make to the brush will be reflected in a greyscale preview. For a colour preview of your brush preset, use the Brush Tool to paint onto the current document (choose a different foreground colour if you want to).

Here’s an explanation of each section of the Brush window and what it does:

Brush Tip Shape Typically used for paint-type brushes, this setting lets you edit a brush’s default size, as well as its angle, roundness, and hardness. You can also set the spacing for the brush bristles.

Shape Dynamics These controls are normally used for image-hose-type brushes. Size Jitter, Angle Jitter, and Roundness Jitter vary the shape of each brush mark (single dab), letting you create, say, fields of wheat in which each stalk has a unique shape.

Scattering Most often used for image-hose-type brushes, scattering varies the placement of each brush mark, allowing for a more natural distribution of paint dabs such as for grass, leaves, or snow.

Texture Ordinarily used for paint-type brushes, the Texture option lets you apply a pattern to each brush stroke to give the impression of texture (such as canvas).

Dual Brush Applicable to all brushes, this option combines two tips to create brush strokes; it places the texture of the secondary brush stroke within the boundaries of the primary brush stroke.

Color Dynamics These controls allow you vary the colour and intensity of your brush stroke, adding even more nuance to each mark that you make.

Transfer This setting applies to all brushes. Opacity Jitter lets you randomise the transparency of each brush mark; Flow Jitter allows opacity variations that flow naturally from solid to clear.

The remaining five options available, mostly used with paint-type brushes, have no adjustable settings.

Share your brush 
Half the fun of creating a new brush is sharing it with others. Choose Edit > Preset Manager. Shift-click on your new brush (or brushes) and then click Save Set. Give the set a name and save it to your desktop. You can now email this file to friends and colleagues. Once they have it in hand, they can double-click it to automatically add your unique brushes to their current brush set.