I feel it is good to introduce people to the teachings of the Ahl al-Bayt (A) through the hadith transmitted from the Imams. So, a good collection of hadith, such as _The Scale of Wisdom: A Compendium of Shi'i Hadith_, or the book that was circulated a couple decades ago, _A Bundle of Flowers_.

Some of the translations of books by Ayatollah Motahhari are also quite lucid and accessible.

Also sharing du'as like Du'a Kumayl.

One really knows more about what Shia Islam is about by reading these types of things and getting a sense of the worldview and understandings behind them, and what the tradition of scholarship is like, rather than some of the more polemical issues (such as the details of how to do wudhu or disagreements over specific personalities), unless the person has a specific interest in certain formal matters of sectarian debate. The essence of the differences between Sunnism and Shi'ism really goes beyond the types of sectarian issues that are debated about, but this sort of thing can be much harder to put into words.