What's the best way to dump 100s of gigs of unsorted images into Immich

I'm hoping to amalgamate many years worth of family pictures. These pictures were taken from various cameras, various family members and are only somewhat organized in their own respected hard drives or SD cards. I'd like to amalgamate all of these images into one collection.

Is there any literature or recommended method to dump such a large and unruly collection of images? Is there any recommended method to store them on my hard drive before importing them into Immich?