Most people think that cocoons are the encasements used by caterpillars to go through metamorphosis into butterflies. Actually, cocoons are the casings of moths and not butterflies; butterflies use chrysalis and not cocoons. Identifying a cocoon is very simple and doesn't require you to be an insect specialist. Remember that cocoons will have moths coming from them, so if you are particularly against moths, you'll want to identify cocoons as a measure of pest control.
Look at the location of the casing. Generally, cocoons are built on tree branches or leaf litter. Cocoons, however, don't hang. They rest against branches or are buried in the litter. Chrysalis can be built just about anywhere and usually hang.
Look at the texture of the casing. A hard and slick, almost insect-like casing is not the cocoon but the pupa that is supposed to be inside of the cocoon. Cocoons are silky, smooth and very brittle casings.
Observe the material of the cocoon. Cocoons are made with different looking materials, with some cocoons looking like dried leaves, some looking like green leaves and some looking like they've been spun by a spider.