Fishing for winter flounder usually involves anchoring. The first step is to anchor the boat slightly upcurrent of your chosen spot and send down the chum basket. Then send down your flounder rigs and wait. Every so often, give the chum basket a shake and scatter some corn or gerbil pellets around the boat. If you don't get a bite within 15 or 20 minutes, try another spot. Of course, some spots produce better on certain stages of the tide, but this can only be learned through experience.
Drifting works best in situations where the fish are scattered over a large area. The drift must be slow, and it sometimes pays to drop anchor and work a specific spot once you get a bite.
The flounder's bite is subtle, and requires an "educated" touch. When you feel the telltale nibble, lower the rod to let the fish eat, then set the hook with a fast, firm upward stroke.