I often start with 10^3 as "number of students in my high school", I have a distinct image of some school photo in the school yard where everyone was on there. After that e.g. the number of images (each showing one yard-full of students) in a photo album. Number of photo albums that could fit in an Ikea shelf. Number of Ikea shelves in a library. Etcetera, though that alone should get you to 10^10 or so.

Imagining grains of sand can get you to bigger numbers faster.