For fire to keep burning it needs a continuous supply of heat, fuel and oxygen. Heat radiates out away from the burning fuel, so a single burning stick will lose too much heat and go out. To keep from losing the necessary heat, place the pieces of wood close together. The smaller the wood diameter, the closer together. Big logs can be as much as 4 inches apart, twigs as little as 1/16th of an inch. For most wood, an inch is good. Oxygen flow is most critical from the time you start the fire, until you put it out. Too much flow (high wind) carries away heat and cools the fire. The perfect amount of oxygen is the exact amount necessary to keep the fire burning at its hottest. Regulate airflow by building wind breaks, and by bringing the fuel closer together for too much air, or further apart for too little air. it's possible to smother a fire with too much fuel. You can also put out a fire by pulling the burning logs apart. Changing the flow of oxygen regulates heat. If there is little wind, the fire will create a draft (a column of rising air) above its hottest spot which will draw in air from the outside. This can be enhanced by building the fire in the shape of a chimney. For cooking, this concentrates the heat in the center and is good for boiling water in a pot, and is a good way to get the fire going, and coals produced. The best cooking fire for roasting, and grilling has an even bed of coals, with heat reflected back in from the rocks on the sides of the pit.
Until I tried it, I assumed if I threw a piece of steak right on the coals, that it would become charcoal. After trying it I found that the steak first sears a bit on the hot coals, but cuts off much of the oxygen supply, gradually cooling the fire beneath. It is often necessary to move the meat to allow in enough air to keep the coals burning. The steak was better than many I've cooked on a grill. Whole trout should be laid on the coals for three minutes, then turned over for another three. Excellent! For coal bread, make up dough cakes about 1/2 to 3/4 inch thick and place on the coals. Turn before they blacken. Test for doneness with a sharp stick. For ash cakes, make very thin pancakes and scrape the coals off of the bottom stones and fry on these. When turning food on the coals, don't put it down on the same spot, as this has cooled. Potatoes, yams and squash are placed in a hollow in the thickest part of the coal bed and turned regularly. Again, test with a sharp twig. Even when black on the outside, they are moist and delicious on the inside, and a charcoal layer keeps out bacteria so they will keep for several days. Corn on the cob should be soaked, then set along the edge of the pit, and turned as the husk gets dried out and begins to burn. Eggs can be poached in half an orange rind, or half an onion with all but the outer two layers removed, carefully placed in the coals. Eggs can be fried on a hot rock if you have fat and a bit of bread dough. Mold the dough into a circle to surround the runny eggs. If you keep it thin, it cooks through as well.