Grab a flashlight. Pretend you’re Sherlock Holmes, but for spider entry points. This is strangely satisfying.
Check your windows. Are screens torn? Fix them. A tiny hole is like a red carpet for a spider. Spiders can squeeze through gaps the size of a pencil tip.
Look at your doors. Is there a gap under the front door? A draft snake or weather stripping is your best friend. Sliding doors also need rubber sweeps.
Don’t forget your pipes. Where plumbing enters the wall, there are often gaps. Stuff them with steel wool. Spiders hate scratching their legs on steel wool.