Some things to look for in first sentences: attitude, intrigue, orientation. Attitude is the mood and mindset of the protagonist. Intrigue is curiosity about the content of the book. Orientation is a sense of place or time to help the reader know where they stand.
I read quite a number of first sentences as samples, but if you want to hear our discussion of each one, I'm going to send you to the video.
Deborah J. Ross The Heir of Khored
Marguerite Reed Archangel
N.K. Jemisin The Fifth Season
Margaret Atwood The Handmaid's Tale
The question "who" is a critical one. Whose voice are we hearing in a first sentence? This person will be your first host, and your first guide to the world of the story.
We looked at the first sentence of Ancillary Justice by Ann Leckie. It seems very clinical in its description of a body. One wonders, "Is this a murder mystery?" "Who could be so clinical and objective?" Both of these questions can cause readers to read on, and the second one is already revealing a lot about the protagonist.
At the beginning of a book, a reader relies a lot on existing assumptions about what is true and possible because they have so little information yet from the book itself. This critical point is where breaking assumptions is most critical if you don't want the reader to continue to rely on them until the end of the book.
Orson Scott Card Ender's Game
Whenever someone is singled out as "the one," we wonder why.
J.K. Rowling Harry Potter and the Sorcerer's Stone
We pointed out the phrase "perfectly normal, thank you very much," and noted the attitude, particularly the sense that someone doth protest too much.
Stina Leicht Of Blood and Honey
We spoke about the word "yabbos." Some of us knew the word, and others didn't. When you encounter an unknown word in a speculative fiction context, you may or may not be inclined to look it up, because many unknown words in SF/F have been created by the author and won't be found in a dictionary! Yabbo, on the other hand, will.
We looked at some first sentences from the discussants. Che brought us an intriguing one with the phrase "bird toes" in it. Glenda's was "Dardith hated Festivals."
Sei Shonagon The Pillow Book
It was written 1000 years ago, but it has a great first sentence full of attitude!
Janice Hardy The Shifter
This is the infamous "chicken sentence" that I remember to this day as an example of a stellar opening sentence.
We spoke briefly about the idea of an envoi. Does it count as a first sentence if you have a quote before the text starts? Certainly it helps to set the expectations of the reader, but readers may also suspend judgment since opening quotes don't usually open the narrative. The opening rhyme I used in "Mind Locker" was intended to set the scene in mood and age of protagonist.
Thank you to everyone who attended. It was an interesting discussion!