To the fly fisher, the wooly bugger is the equivalent of the jig to the spin fisherman. Each would be in about 99 percent of the "If I were limited to five flies/lures" lists of each respective pursuit.
Like the jig, the wooly bugger can be fished in a variety of ways and conditions, explaining the large part of its exceptional utility.
During the early season, when the water is often high and off-color, the wooly bugger excels when fished as either a wet fly. Simply make cross-current casts, allowing the fly to sink as it slowly drifts downstream by making the necessary line mends to minimize drag. At the end of the drift the fly will slowly raise, a movement that often provokes a strike. Cone or bead headed wooly buggers can be particularly effective during the early season, since the added weight helps the fly attain added depth. Not surprisingly, a bead (or cone) headed wooly bugger strongly resembles a jig.
The wooly bugger can also be fished as a streamer, where the angler imparts movement by way of rod twitches or line retrieval. A good tactic is to allow the fly to dead-drift during part of the cast, and then give it some action toward the end, like when it's on its final swing as the line straightens. This movement suggests an emerging insect struggling to the surface.
Though the wooly bugger is typically thought of as a spring or fall fly, I find it particularly useful during the summer months on small streams that hold wild trout. These runs are freestone (as opposed to limestone) in nature, and as such have limited food sources. The trout in them don't pass up many meals, so fly choice often has more to do with how efficiently it fishes, rather than representing any particular bug or minnow. The wooly bugger is a great fly to pitch along an undercut bank, near a plume of water entering a pool, or near the overhead cover of a downed tree trunk. It's almost like pitching a jig near heavy cover for largemouth bass.