When you meet someone, what do you notice? Some people notice eyes first, others look at the person's hair, and still others notice nontraditional things like shoes or blinking rate or whether their eyebrows meet at the top of their nose. Now, when you go to someone's house for the first time, what do you notice? Maybe you peer at the person's kitchen, remark on minor details like what kind of china they have or whether they use a sponge or a dishcloth to wash dishes.
When I enter someone's house for the first time, I always stray towards their bookshelves. What are people reading, what have they read, what do they intend to read? In what order do they display their books? Is their reading material abundantly scattered throughout the house, or is it all collected on one bookshelf?