Look at WCAG 2 (web content accessiblity guidelines) they specify tags and elements common screen readers will understand to help make you site accessible.

This is a really good resource: https://accessibility.18f.gov/

A lot of frameworks now have some accessiblity built in if you add the correct attributes.

I suspect you're being glib, but you could look at https://wiki.openstreetmap.org/wiki/OSM_for_the_blind