The conventional method: To hang your food up and away from bears and small, hungry critters, locate two trees about 20 feet apart. Throw a weighted end of rope (50 to 100 feet long, at least 1/8-inch or thicker nylon) over a limb that's at least 17 feet off the ground. Tie the rope to the tree.
Toss the other end of rope over an equally high branch of a second tree, and attach your food bag to the rope's midpoint.
Hoist the bag and tie the rope to the base of the second tree. Make sure the bag is at least 12 feet off the ground.
The counterbalance method: If there's only one suitable tree in the area, locate a branch that's at least 20 feet up, sticks out at least 10 feet from the trunk, and is about an inch or 2 in diameter (strong enough to hold the food bag but too thin to support a bear). Toss the weighted end of the rope over the limb.
You'll need two stuffsacks of equal weight for the food, ideally less than 10 pounds each. Tie a retrieval loop and the first sack to one end of the rope. Pull it up. Tie the second sack on the rope as high as possible and add another loop. Put excess rope in the bag.
Toss the second sack up so the two balance evenly, at least 12 feet off the ground, 10 feet from the trunk and 5 feet below the branch. When time to eat, hook one of the loops with a stick and pull the bags down.