I am not doing anything special to prepare for a couple of reasons.
One I don’t live anywhere near a target, unless Bin Laden wants to kill a bunch of cows. And two, the technical difficulties of pulling off an NBC attack is most probably beyond the terrorist, at least at the moment.
Biological would have a limited effect in America. Our hospitals and emergency crews would be able to detect and respond to the attack very quickly. Basically unless you were one of the unlucky group that was initially infected you would be fine. I would recommend practice good hygiene for the next few months though; wash hands before eating, etc, etc. Just the standard things that cut down on disease transmission.
Chemical, very difficult to deliver. That Japanese cult tried it several times with no effect until they finally killed 12(?) people in a subway. Also unless you very careful with chemical weapons you just end up killing yourself. Chemical is even less scary than biological.
Nuclear. I don’t believe they have the capability. For one suitcase bombs don’t exist. Small nukes were made but they had to be carried by two people and were about the size of a duffel bag and weighed about 100 lbs. I don’t believe the Russians lost any of these weapons. Honestly if the terrorist had any of these weapons they would have used them already. Worst case scenario if they did have one or two remember these bombs are not city busters, they torch about a ¼ mile radius. If one of these goes off they are very survivable (as long as you’re more than a ¼ mile away) just get away and make sure your not downwind.
Jelly
P.S. I also think of the Brits in WWII. Their country got bombed daily and they held up. I think we will be ok just dont panic.