I've tried a few different ways. What I have found to work best so far is to have a couple of large logs on the bottom, then build a fire on top of that with finger sized pieces of wood. I keep the fire fairly small but keep on adding the small wood - my idea is that the it is easy to get these burning and although it takes some maintenance for 10 or 15 minutes, it seems to be a good way to get some heat into the oven which then helps once I start to add slightly thicker wood and then push the fire to the back/side of the oven, where I add progressively bigger pieces of wood as the fire gets well established. I am trying to avoid the temptation to mess about with the fire too much, but I'd be lying if I said I always resisted!
I think I must fiddle too much, I have also had the small fire but once I move it back it seems to die down, I can get it back with plenty of small bits but it seems to make a pile of embers then and when I place a larger piece I think perhaps it does not get enough air flow to fully burn.
I have finally managed to get some wood dried in the hot oven, so want to try to start the fire larger than normal with these and see if I can get some more logs in at the start so there is more fuel to burn between fiddling as I think my issue is I never load it up enough so when I leave it burning well it does not last.
Turkey. Although i am using fairly small pieces of wood, i build the fire on top of a couple a big pieces of wood, so eventually they start to burn well with the embers and heat from the initial fire. Thats when i start to use bigger pieces of wood.
I had the best burn using the idea like Faz'. But i pre-loaded the rear of the oven with log. Then occasionally, and i mean occasionally threw a 1-2" Kindlog in, to bridge over once the mid oven fire was going. Sort of kiln drying as you go.