Step 1: Materials
Iron that can steam. Alternatively, you can produce steam with microwaves, stoves and ovens. I've never tried these methods, but theoretically they should work, too.
Discharge paste applicator, eg fingers, but more likely a paint brush, available at both arts and craft stores and hardware stores. Maybe even the SuPeR market if you get a meat baste-er.
Natural fiber fabric with pigment (not paint).
Optionally: cardboard to make stencils, or silk screen.
Step 2: Create Stencils or Silkscreen
Cut it out. I used a cheap swiss army knife I found lying around, but an exact o knife would also work well.
You can make stencils with multiple pieces. These ones are simple.