Depends on the body of water. If there is green submerged weeds, then start your search there, anywhere from 3' to the weedline, paying particular attention to bare spots inside the weeds and any points or indentions on the weed edge itself. If there isn't much vegeation or the vegetation is brown, I would check any drop-offs near the largest expanses of shallow water on the body of water you are fishing. Especially good are isolated deep spots in shallow bays.
Plan on drilling lots of holes and covering water. When you get into them good, you will be marking three or more at a time on the flasher.