HELP. How do I lower the heat in my smoker if it gets too high?

Run-a-way fires are the hardest thing to bring down in a charcoal or stick burner. Your best recourse is to have a metal fire bucket that you can put burning wood or charcoal into. Even damping down a fire 100% can take a while to reduce chamber temps - and if you close off the exhaust damper you run a real chance of creating creasote all over the meat and inside of your smoker.

I had a friend who competed with a couple of WMS's and they had a run-a-way fire at a competition. They had a large 5 ft. x 4 ft. aluminum pan (used for putting under cars to protect garage floor while working on them), and they had to just dump the entire fire bowl out onto the pan and start over.

Stick burners are a bit easier because you can pull the logs out one at a time if they are still intact. Either way you can pull the meat and put it in the oven while you straighten out your smoker, then put the meat back in the smoker.

Close down the fresh air. If the temp is not dropping fast enough open the cook chamber for a quick temp reduction and continue to watch, opening the fresh air damper as needed to recover temp. With the exception of Cheese, 25-50°F swings that last no more than 30 minutes will have zero effect on the finished product...JJ

Here's a bit of help : http://www.smokingmeatforums.com/a/stickburning101

have fun and . . .

Add another air inlet ABOVE the fire.... that will allow cool air to enter the Fire Box and NOT allow more air to the fire.... It is an easy way to regulate heat...... The inlet should be higher up than the picture shows.....

Great advice form all the above. It takes several smokes to get your smoker figured out and get comfortable with the adjustments. If you started with a pretty big fire, cut back next time. The only thing I use to regulate my heat are the Firebox dampers. I did install an upper damper on my door as Dave suggested, makes a huge difference. 

Gary