Budget food/living

Any tips on keeping the house warm on the cheap over the winter? We're going to try to hold off on using the gas heating until Novemeber.

We live in an old building with wooden windows, so will fitting that foam insulating tape help much?
I saw adheisive screening you can buy enabling you to cover whole window sections entirely. Are they effective?

Duct tape. Seriously. Duct tape every hole you can see or imagine seeing. Stand in drafty areas and duct small animals into any gaps! Such a change from a year before of ice cold drafty living.