The best tactic is either to fish smaller single baits on or just off the bottom, or a zig bait higher up in the water. You should also be fishing during daytime and seek out either the deepest parts of your venue or if there is warming sunlight, shallow areas with a lot of vegetation.
The best way of catching cold water carp is by using 12-16mm fruit-flavored baits on the simple hair rig or the pop-up rig. You can significantly up your chances by fishing in deeper water during the day and in milder weather conditions. Drop-offs are a real hot spot for cold water carp and should never be disregarded.