To keep a drafty house warm you need to seal off the drafts that allows cold air in.
For example if you have drafty old windows you should clean the old caulk and reseal the windows with new caulk.
If you don't need the window to look out of then you can also put some foam insulation between inside the windows and then put some plastic window shrink wrap over the windows and also use a heavy curtain or blanket over your drafty windows.
Use those draft stopper door seals on the bottom of your exterior doors or roll up a towel as well.
Also consider using some door and window weather stripping to seal drafty doors and windows where there may be cracks in the door gap and window gap.
When the walls in your house are so cold it's caused by a lack of insulation or not enough insulation.
If you feel your walls and the plaster or drywall is cold either you have no insulation behind those walls or there's not enough insulation.
Insulation has different types depending on the zone you're in so it's important to install the proper R Value of Insulation or your home can be too cold in winter and too hot in summer.
In older homes such as those homes with plaster walls or 100 year old homes they had no insulation behind the walls as the insulation we use today was not invented yet.
I live in a 100 year old house myself and I have insulated most of the house when I remodeled and took down the falling plaster and put drywall.
However my Kitchen and bedroom walls have good plaster and no insulation in behind the walls.
So I can feel the plaster and the walls are cold when it's cold outside.
I plan to rip those walls down hopefully in the next few years and do remodeling and adding insulation but for now I have to deal with it.
If you have inadequate wall insulation, wall tapestries are an easy decor fix that will help to warm up your rooms.
The heavier the material, the better.
A quilt will also work.
You can even create a fabric feature wall by applying fabric like wallpaper to one or more walls in your space using liquid starch.