Why start out with "I've Been Workin' on the Railroad" again? Because it's lively, tuneful, popular, and runs by itself. But, maybe you'd like to be known as a good song leader instead of just a good song leader. Then choose songs appropriate to the occasion and the mood you want to create. Here are a few suggestions from the Scout Songbook, No. 3224. There are lots more there-but try the new as well as the old.
Write a "program" of appropriate song titles on a 3" x 5" card for each campfire or meeting where you will be responsible for the song leading. Write big enough to see in dim light. See Leading Songs for a few tips on using singing effectively.