Question

what advice would you give someone about how to collect light to shine into a microscope?

Answer 1

Adjust the Mirror Properly according to Sunlight ⛅

Answer 2

Hey mate I know the answer :

The simplest illuminator is a pivoted mirror to beam external light to the microscope. It's used to direct room light, lamp light, or skylight from below the scope's stage up through the specimen as transmitted light. Mirror illuminators most often have flat and concave sides.

Hope it helps.