- It has a great hook.
- It teaches me something new.
- It’s the first. Or the best. Or both.
- The author has the self-promoter gene (in a good way).
- The subject and/or the author are particularly web-friendly.
- The subject lends itself to a great physical package.
- It features a smart person writing on a fun subject.
- It’s similar - but not too similar - to books we’ve done well with in recent memory.
- It has crossover appeal.
- It’s quirky/surprising/memorable.