There are many cold weather problems in your home, or at least the typical home I see when doing energy audits. Comfort problems exist in almost every room. There are common issues in most homes that can easily be fixed. It just takes time to identify the places where you can make big changes. Such as making sure your attic access has insulation on it. You also need to make sure that the entire access panel fits tight and has weather stripping around the opening.
Doors that lack weather stripping is a problem all around the house. I see a lot of solid wood doors that have no seal. These are the worst offenders for air leakage.
Air leaking in and around electrical outlets is another common issue. Sealing the plastic box tight to the drywall and adding a pre-cut insulation gasket behind the decorative cover will help this problem.
Recessed can lights are a huge problem in homes. I know some are “air tight” but even those leak air into the conditioned space.