This tutorial is a step by step method of developing characters that appear authentic to graffiti street art.
Open a new file having
1024x768 px and
72 dpi. You may use a brick wall as a background for the picture.

Press on
Shift button and make use of the next instrument

to represent a lot of circles colored in
5D5D5D.

Set
Overlay on the layers.

Insert the same way a lot of other circles, colored this time in
505050.

Set
Overlay on the layers too.