To seal cockroach entry points, identify common areas like cracks in walls, gaps around windows and doors, and openings near utility lines. Apply silicone-based caulk to seal cracks and gaps, as it is flexible and long-lasting. Seal spaces around pipes and electrical conduits with steel wool or copper mesh before applying caulk to deter cockroaches. Install door sweeps on exterior doors to eliminate gaps at the bottom where cockroaches can enter. Maintain cleanliness by regularly cleaning areas where food and moisture accumulate to reduce attractions for cockroaches.