Clean the window frame and sash
Remove old caulk, putty, or weatherstripping
Inspect for gaps, cracks, and damaged seals
Apply exterior-grade caulk to gaps around the frame
Use weatherstripping on movable parts of the window
Replace worn or missing window seals
Install foam tape for small gaps
Add a window film kit for extra insulation
Use rope caulk for temporary sealing
Check and seal the exterior trim and siding joints
Repair or replace damaged glazing putty
Tighten or replace loose hardware
Test for drafts after sealing
Reapply sealant as needed over time