1.first you have to draw out your brush with any brush you want. (only in black)... it could be any shape you want... the more unique the better:)
2. After you have the silouhette for your brush... then you go to Edit> Define Brush Presets> Name your brush
3. Voila!!! you have your brush!!!!
****Also... you can save your Brush Presets in the "TOOL PRESETS."
go to window> tool presets>then in the top right corner option box select > New tool presets> Name your tool Preset
You can make it as personal as you want, you can even set your tool to a certain color or anything!!!