Photoshop Sensei: Creating a Brush from an image or a photo

Where to start
I start by looking through my photos to find an image I'd like to make into a brush, this can be for many reasons, I find it is often for website development as a photo itself can make a page looks aesthetically displeasing (ugly)
where as a brush would fit in perfect!
Now for the Brush creation:

Step 1 - Double click on the Background layer, name the layer (although layer 0 is fine for this task) and click ok. This is an important step for deleting the background.

Step 2 would be the cropping,
I try to crop as close to the future brush as possible.(the backgrounds getting deleted anyway!)
If you don't know how to Crop, you can find my step by step guide HERE.

in this case the horse and rider.

The next step is selecting the brush, I start with the Quick selection tool (tutorials coming soon!)

Note that to fully select the outline I used forbidden ninja techniques! (Selection tutorial up soon!)

Once selected, go to ctrl+shft+i or Select->inverse(to select the background)
I now have 'marching ants' around the out skirts of the image, then the background is selected.

Step 3

Now that I have my Brush, I go to Edit->Create brush preset. (may have to select all first, ctrl+a or select->select all)

Now I simply open a new document to test my new brush!

I select the brush at the top and click the tiny arrow to drop down the brush presets, scroll down to the one I just created and double click on it. Note that the size will be the original size of the image I selected which means two things, one is that it is VERY LARGE and two is that if you make a brush from a small image - there is a better scalability out come. (does not turn as pixelated as an image you try to stretch).

Also note that you can resize the image if you have no need for a Large brush, however I find just making the brush smaller works fine.