Here's the part where I blend some abstractions into the image. You can either steal some abstractions from deviantart, or you can make them yourself with abstract brushes.
A good place for abstract brushes is JavierZhX's deviantart gallery channel (if you want them, search after Abstract ?insert number here? in his gallery). However, the brush I'm going to use is Shadow-gfx's Abstract Fury Brush Set
When you have a brush that you want to use in photoshop, place it in your Adobe Photoshop CS3\Presets\Brushes folder.
Now I will make a new 800x600 image, make the background black and create a new transparent layer over it.
Now I will have to select the brush that I want to use, which I can do by first selecting the Brush Tool from my sidebar, then click the brush pattern that's to the right of the Brush: text in the top left corner. Then I will click the arrow that's pointing to the right in the box, and a number of brush names will appear. Select the abstract brush that you want to use (it should have the same name as the filename of the brush).
Now I have serveral abstract brush patterns to select between, so now I can mess around with them in my transparent layer, what I have to remember though is to make my brush white and don't press more than 1-2 times when placing an abstract brush pattern.
Things that you should think of when you make your abstract picture is:
1. Don't use the same brush pattern too many times, make sure that you variate yourself
2. Don't place your brush patterns at the same place too many times, it can look neat sometimes but makes it a mess
3. It can work sometimes but keep in mind that you shouldn't use two different brush sets in one picture.
4. Try to fill up the biggest black places with abstract brush patterns, smaller black places doesn't really matter that much
If you follow these terms the picture will usually end up nice whatever you do.
After messing around with my brushes for a while my image will end up like this
[Example image]