A little biology lesson here to reinforce what you've already been told.

Respiratory infections in snakes are much more serious than in many other animals, because snakes do not have a diaphragm muscle like you and I do. Hence, they cannot cough the way we can to help clear congestion out of their lungs. As already mentioned, pneumonia is a real threat, as the inability to cough allows fluids to build up in the lungs much faster than it would in other animals. The more fluid in the lungs, the less oxygen that gets into the bloodstream.

I'm using a 50 Watt red heat lamp bulb for my BP to bask under, and I also have a 7 watt under-tank heater at one end of the tank. If you use an undertank heater, (the 7 watt size can be bought for around $20 from a place like Petco), make sure you have a good layer of substrate so that the snake cannot get directly against the glass over the heater. The glass can sometimes get hot enough to cause burn wounds if the snake gets directly against it. To monitor temperature, I use a simple suction cup attached home thermometer I picked up at Walmart for about $3. It might look kind of silly having a thermometer with a cute picture of a Cardinal on it, but it works just fine. Humidity checking is a little tougher. I'm finding that inexpensive hygrometers are not exactly real precise. I have two in my terrarium right now. One reads less than 20% humidity, while the other reads closer to 50%. I think this weekend I'm going to break down and pick up a better quality one that's a bit more reliable. That is, if I decide to brave any stores on the weekend after Thanksgiving shopping rush...

Good luck, and please keep us apprised on how things are going!