I've been a Popcorn Kernal for 7 years and counting. Its the major fundraiser for our troop and its done well by us.
We also do wreaths, Tom Wat, Rada and flower bulbs too. For all of you with the deadline disease. Question: Do you want the kids to sell popcorn or meet deadlines? That is what i told our concil poohbahs at the kick-off meeting. The key here is flexibility on the councils part. They tried to get hard line this year and thankfully they have backed off. I've learned a few things along the way. Those kids who are truly motivated to sell will do so year after year. They like making the money and watching their scholarship grow with Trail's end. The rest of the boys will only sell if the parents want their kids to pay their own way through scouting. Most of the time the parents wind up footing the scouting bill. We have put our foot down though on families who want camperships because they don't have the money. If they didn't make a good effort to raise funds there won't be any camperships for them. BTW I go out to the community to raise funds for that purpose too.
The best motivator though for the kids is to have a specific goal for the troop to work towards. For example, a trip that the troop wants to take would require X amount. Make that the goal and the kids will work more diligently toward it. IMHO.