Customised Brush tutorial

Here's to all you up for giving this a try... Something that has helped me trememdously lately and that I'm more eager than anything to get to using more often... customised brushes.
I decided to leave most of the fancy 'create your own base' stuff, the simple thing that can already open a door to people that never thought of trying it before.

I was inspired by the effects I saw in theworks of other artists and decided to mess around and try to see if I could recreate that. For some of my initial tryouts, it was mainly stuff like this: [link]

Please let me know if you see any typoes or things that are unclear, or something you think I should explain futher.
The character in the little sloppy painting is Gordon, btw.
Pen pressure died, but I'm sure I got the point down.