Early Winter and Late Winter are fabulous. Mid-Winter usually sucks unless you know of a select area (or two) where fish occasionally get active, and learn through trial&error when to hit them.
A couple of the spots I know about are "community holes" that get hit pretty regularly. Everyone that hits them will usually catch one or two, but the guy that is there when the real magic happens will load the boat almost effortlessly.
After over 25 years of living here I can't explain when that time is, but with one specific spot sometimes I can just feel it, and more times than not I am right. Total gut instinct type stuff, it makes no explainable sense whatsoever.