Pull the pin out, and drop out the firing pin. Push the bolt in, turn the cam pin 90 degrees, and remove it. Then pull the bolt out of the carrier. Using a small punch, push out the extractor pin on the bolt as you push down with your thumb on the rear of the extractor, then remove the extractor.
All the gas and carbon flowing back into the receiver blows directly into the front of the carrier at the gas key. This area gets filthy with carbon, and of course the dirtiest portions are also the hardest to reach. After cleaning, don't try to lube specific parts, just spray Remoil or CLP on everything as you are reassembling. High stress areas that should definitely get a squirt of oil are the cam pin, cam pin recess, and the area where the bolt rides. Most everything else will do with a light film of lubricant.