Energy savings for an apartment? We need suggestions please.?

The coming cold and snowy winter will be our first in an apartment. Our bedroom has an east and a north-facing window with multiple panes. Our landlord will let us do anything to reduce utility bills. We have a gas heater that gives radiant heat--it is situated between the kitchen and the bedroom. It is a one bedroom unit and we share only one wall with another tenant. This is at 7500+ foot elevation and at times we'll have 3 ft. of snow on the ground.