Empty out the ash from the previous burn. Gently scrape over the grate with a stick to make the ash fall down, leaving charcoal. Rake out the ash from the ashpit (below the grate) using a stick or L-shaped metal rake. Don’t invert, tip or shake the stove to remove ash – it might fall apart.
Put a layer of charcoal onto the grate, about 3cm deep.
Take a piece of torn-up waxed cardboard kindling, light it, and push it into the ash pit when burning strongly. A pair of tongs makes this easier.
Fan into the ash pit door, to force the flames up onto the bottom of the charcoal.
Once you can see plenty of red fire amongst the charcoal, it can be left to keep heating by itself, or fanned more to make it hotter sooner.