What are the three most important winter tune-ups needed for a Wisconsin winter? on 1992 Buick Century

Changing/flushing coolant is an obvious one. However are there any other biggies that I should take care of before the winter sets in? I don't want to spend $1000's on repairs... especially since this is an 19 year old car. I just want to tune up the essentials so that it is dependable through the winter.

Asked by for the 1992 Buick Century