What rainbowchaser said.

I usually tie mine with yarn for the body instead of chennile and palmer with the cheapest hackle can find. If I want them to sink a little faster, I put a few wraps of lead wire on the hook shank or a bead head.

I've found a very effective color combination is a butterscotch yarn body, a little tuft of red yarn about 1/4 hook shank length sticking out the tail and light brown barred hen hackle palmered up the body. Some guys counter wrap wire through the hackle but I've not been using that for a couple years now and have seen no difference in how the flies hold up.

Depending on what you're fishing for and where, is how you retreive them. I use them a lot in ponds and lakes for bluegill. I find an agonizing slow retrieve with a few twitches here and there drives bluegill wild. I've also landed a fair number of bass and crappie with these things while fishing for bluegill. Truth be told, I catch more fish on a woolie worm than I do with a woolie bugger.

Jeff