This is a list of books that in my opinion every convert (and every Jew) should have, besides of course books that explain Judaism:
- A TaNaCh, the Jewish bible. Best I think in both Hebrew and translation to your language, side-by-side or in two books. It is important to have a Jewish translation as any translation is also an interpretation. If there is commentary, obviously it should also be a Jewish commentary.
- A Siddur, the prayer book for normal days and small holidays. I have the pocket-size Hebrew-English Artscroll siddur, I like the size, the layout, the font and the instructions very much, but the commentary is very right-wing orthodox, so this might not be for everybody. And obviously ArtScroll has the traditional text, no matriarchs, no alternative female forms, no prayer for Israel. I also have a second Siddur with transliteration which I give to my guests so that they can follow the service without speaking Hebrew. Before you order a siddur, try out the ones they have at your synagogue and find one you like.
- Several copies of the Birkat haMazon, the prayer after meals. You can buy small booklets that also contain songs for Shabat, Kiddush, Havdalah and such stuff, but you can also just print the prayer out from the internet (in a way that looks somewhat nice). You should have one for every person who eats with you, so if you usually have eight people at Shabat dinner, I’d say you should have eight.
- A Machzor, the prayer book for the holidays. They usually have those in large numbers at the synagogue, so you don’t really need buy one right away, but it helps to have one to prepare for the holidays. You will need a machzor for Rosh haShana and a (different) machzor for Yom Kippur. Some Machzorim include both, some are for one holiday only, it doesn’t really matter. For the other holidays (Succot, Pesach, Shavuot, Purim, Chanuka) a normal Siddur should be enough, as the changes in liturgy are not as extensive. As you will only use your machzor once or twice a year, it is very important that the layout and the instructions are easy to undestand and intuitive.
- A Hagada for the seder on Pesach. In fact, probably you should have at least two, a simple one with only the text and translation to follow along during the seder, and another one (or more – over time!) with commentary to better understand the text and prepare. If you are invited for Pesach, they will usually have a Hagada for you, so you can get by without one. Conversely, if you invite people and don’t specifically tell them to bring a Hagada, they might expect you to provide one.
Aren’t we the people of the book(s)? 😉
Additional suggestions welcome in the comments!