Rules for Choosing Sides:

"1. Leaders choose sides.  Don't let two boys choose the sides because

2. Pick sides by counting off by twos or by randomly picking two boys
of similar abilities and putting one on each side.

Other variations:

2b. count off, using variations on occasions to prevent scouts from
strategically switching themselves (e.g.1-2-2-1-1-1-2-2-1-2-1-2-2-1-1-2)

2c. get everyone to line up "tallest to smallest" and then split off
1-2-1-2-.. The teams rarely were the same because there's always
someone missing, and the kids grow up. It also tends to produce
physically balanced teams for games where it matters.