This is a really easy technique with such cool results!
You are going to need to do a bit of testing first to see if the bleach will work on your fabric. Bleach doesn't develop the same on every fabric. Just use some small swatches of different fabrics and paint a little bleach onto it and leave it to develop for a while. Once you've picked the fabric with the coolest result you're ready to go.
It's much easier to paint onto your cut pieces than a made up garment as you want to have a couple of layers of paper underneath so that the bleach doesn't seep through.
If you're going to paint a directional design like we did, it's good to lay your pieces in the order that they are going to go together so that you can get a clear idea of what you're doing.
It's very simple... start painting. Make sure you're in a well ventilated room, it's pretty hard core painting with this stuff! Within minutes, where you've painted will start to lighten.
Once it has lightened to your desired effect, rinse your pieces well, then rinse in vinegar to neutralise the bleach. Voila! How cool does it look?!
This is the reason I said to use cheap paintbrushes. This stuff dissolves them, so you need to paint fast :) Have fun!