Hi pamom,
I understand being nervous in front of the parents, but just realize that you are the one up there giving your time, and they really aren't in a position to judge! Especially since there are 15 other Scout's parents out there that did not make the commitment to volunteer like you did.
My philosophy is that I will "do my best" and if they ever have a complaint, they are more than welcome to take over from me. We had 8 Tigers last year with me as Den Leader, and parents hesitant to help out - this year we have grown to 15 wolves, and it was like pulling teeth to get a 2nd den leader.
The fact that you are taking on this role means that you are doing more for the boys than they are, and don't worry about what they think. Do what you think is good for the boys.
Ken