Blender: Building Abstract Stuff

How can you build abstract stuff? Where can you begin and which tools could you use? This video tutorial tries to answer these questions, (though it takes a lot more than one video to get an answer)
you should experiment, try stuff, break stuff, succeed, fail and try again. Be playful, use the modifiers and particle systems, change your lights, render settings and materials and see what you get. But what's more important; have fun!