I really recommend (if you can get a hold of it) to start with  Ágota Kristóf 's The Illiterate , because:
1. It explains part of her life (which gets reflected in her works, like The Book of Lies Trilogy and Yesterday) 
2. You understand deeply why her prose is the way it is.
3. It's like 50 pages. This is not gonna take you weeks unless you choose to read and reflect that long. 

I'm not saying you can't learn that from other places, but it gets you right at home with her alienation.

The alienation is very present in this book. And the book is very fucked up, but it's a masterpiece.