8. They can't cost more than $99.
If smartwatches are going to be an accessory rather than a central device, they can't cost more than what people would pay for an accessory — e.g., a high-end headset or a Bluetooth keyboard. Ninety-nine dollars is about the upper limit for such a thing. Charge more than that and you're asking people to buy something that must also work as a standalone device.