Minion Method Start - Named after Jim Minion. Fill the charcoal ring with unlit charcoal (your choice of lump or briquettes, briquettes will typically last longer). The amount to use depends on how long you are going to be cooking. Arrange the charcoal so that there is a depression in the middle Some guys stick a coffee can in the middle and then pull it out. You want a sort of donut of charcoal. Then pour some more charcoal into a charcoal chimney (go buy the Weber chimney if you don't have one). the amount in the chimney depends on the temp of your cook. About 1/2 chimney (maybe less) for a typical low and slow cook. Light the charcoal in the chimney (use a wad of newspaper, a starter cube, a paper towel soaked with cooking oil, your choice) and when the charcoal in the chimney is fully lit (covered in white ash) dump it in the middle of the donut in the base of the WSM. Then assemble the WSM.
Catch the temps on the way up - Start with all of the vents wide open and watch the temp at the dome (if you don't have a thermometer in the dome you can stick one through one of the top vents. A digital thermometer with a probe on a wire is great for this. As the temp climbs towards your desired temp (say 240 for low and slow) begin closing the bottom three vents. You really don't want the temp to go higher than your desired temp if you can help it because it takes a long time to come back down. If it does get too hot just close the bottom vents more and it will eventually come down. Make small adjustments and give the WSM time to react. Once you have it at the right temp you probably won't have to touch the vents for hours. BTW, I leave my top vent wide open all of the time. Others will use this for fine tuning the temp.
Put your meat on - Have it seasoned and ready to go. Don't worry if the WSM temp drops when you put the meat on. You just stuck a large, cold object in there. it will recover.
Check your temps in a couple of hours - Just to make sure. i usually check it 30 minutes after putting he meat in and then again in a couple of hours. Resist the temptation to lift the lid. If you're lookin' you're not cookin' :-D
Check again in 8 hours - This is the real beauty of the WSM. You can set it and forget it. Of course, if you really want to you can set a chair next to it, grab a cooler of beer and pretend to have to keep an eye on it :-D
That's really it. Go cook something! chicken is good since it is cheap and is a relatively short cook (two to three hours for a whole bird). If you want to attempt something longer a pork butt is great because it won't care if your temperature control is sloppy. Invest in a remote thermometer hat you can stick in the meat so you can monitor the internal temp without lifting the lid. cook the pork butt to an internal temp of 195 - 205. Test it with the thermometer probe. it should slide in like it is going into butter.