Which doors should I draught proof?
Air most often leaks into the house through the bottom of outside doors. A cheap solution would be to put a rolled-up towel along the bottom of the door or to buy a door snake. But for a more permanent solution, install a plastic or metal door seal with a wiper that will not only eliminate air leaks but will also stop insects, noise and dust entering the house.
The edges of doors are another common spot for draughts, but this can easily be solved with self-stick weather stripping. Weather stripping comes in different lengths and widths so measure your door first and get the strip cut to the right length to make sure you achieve the best results. There is a more permanent door seal, which is more expensive, refer https://www.ecomaster.com.au/draught-proof-essentials-front-and-back-door-kit/