The Holy Apostles Convent have wonderful books. But, perhaps you can search on the internet and find a particular saint that would help your friend. There are so many Orthodox websites. Let God guide you. And may I add that if your friend has a particular issue about an aspect of the faith, then we can find a story of a saint that dealt with that.
But, for starters, if you want true Christian faith, then at this time of year, I would suggest St. Nicholas of Myra. He is loved by all. And she could be exposed to the true story of St. Nick. And to follow along on that thought, if it's difficult to choose, then why not give her the life of the saint of that day. God will speak to her, in His own way.
These are just a few suggestions.