If you are looking to learn about saints in general, I would go to newadvent.org and look at their catholic encyclopedia. I’ve never been unsuccessful in finding a saint I was looking for. It may be helpful to narrow your search a little as there are TONS of saints that you can learn about. If there is a certain thing that is close to your heart, look up for the patron of that particular thing or look up the virgin martyrs if that interests you.
You can also get books that have a saint every day. Or if you look at a calendar, you could learn about the saint who has a feast/memorial on that day.
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