The brush and paint tool options help you create hundreds of different brush strokes. Play with the options until you get the effect you want.
Size Determines the pixel size of the brush. Note that you can adjust the Size value via the keyboard as well as through the Tool Options palette.
Hardness Determines how sharp the edges of the tool are. Setting this to 100 gives you the sharpest, hardest edge; setting this to lower values gives you an increasingly softer, fading edge.
Step Determines the distance placed between applications of paint during a single (continuous) paint stroke. Lower Step values yield a smoother, more continuous appearance; higher step values yield a choppier appearance.
Density Determines the coverage of the paint step. (For the Eraser tool, this setting determines the level of erasing.) Higher values yield complete coverage; lower values yield spottier coverage as though you're spraying the paint. Note that when using the Airbrush tool, you should set Density to values lower than 100.
Thickness Determines how wide the brush is. Setting Thickness to 100 gives you a completely round or completely square brush (depending on the Shape setting). As the Thickness setting decreases, the brush becomes increasingly narrow.
Opacity How well the paint covers the image surface. At 100% opacity, the paint covers everything. At 1% opacity, the paint is almost transparent. For the Eraser tool, this setting determines the level of erasing.
Blend How painted pixels are blended with pixels on underlying layers. The blend modes are the same as layer blend modes; for more information, see About Blend Modes.
Continuous Stroke Specifies whether paint builds up as you apply multiple strokes of less than 100% opacity over the same area. If this check box is marked, paint maintains a continuous color and repainting an area has no effect. If this check box is cleared (the default), each brush stroke over the same area applies more paint; the color darkens until it reaches 100% opacity.
Wet Look Paint Mimics wet paint, with soft color inside and a darker ring near the edge. Decrease the Hardness setting from its maximum of 100% to see the effect.
Paint Behind Works on layered images only. When a layer is selected, Paint Behind paints behind the data currently on that layer. No paint will be visible when the topmost layer and active layer are both fully opaque.
Once you have set brush options, set additional options on the Brush Variance palette, see Using the Brush Variance Palette.
Painting with the Paint Brush or Airbrush