It depends a bit on how dry it is and the texture for how fine you should bust it. Usually I would just rip it into chunks about the size of a medium-ish pebble (vague, lol, generally less than a centimeter). If it's really fine and dry then it can burn really quickly and you feel like you have to smoke it all at once, which isn't really fun imo. I'd rather smoke it more slowly and that's also more efficient because a lot of heat destroys the actives. Then you can just cover the bowl after taking a hit with your hand, and this will put out the embers so you can take some time without worrying about it burning on you. You can use matches, but you should wait until the sulfur is burned off, or it will taste really bad, and that's kind of a pain in the ass. Personally I would just buy a cheap disposable butane lighter from a convenience store or something. Also you try to direct the flame to one corner of the bowl (I think they call this 'cornering the green') instead of just incinerating all the green from it immediately. Basically you let the flame penetrate deeper into the bowl in a small corner, rather than covering the entire thing, so some green is preserved until the end. This makes it taste a lot better, because once it's all charred and black it doesn't taste so great anymore. This is also good group session etiquette as then the people later on in the cycle aren't left with the gross char tasting stuff.