Google Glass is a lot like my homemade wearables. The resolution and field-of-view are fairly low, input is stripped-down, and a phone is involved. Here are some things I learned in the field, while using my own heads-up displays, that all hopeful Glass designers must know.

1. Input is Your Enemy – Voice is imprecise, gesture is weird, and the touchpad is crude. Asking the user to interact with your app is a real imposition when the app is on the user’s head.
2. Ambient is Powerful – My favorite HUD app I wrote simply showed me the three tweets nearest to my location. I walked along Broadway from Harlem to the Village reading people’s minds and absorbing the scenery. This experience can only be done on wearable.
3. It’s a Magic Circle, Not an App – You’re changing the wearer’s senses and giving them superpowers. It sets them apart from other people and changes their motives. Your app changes the user’s world – it’s more of a pretense to do new things than a tool to make existing things easier.
4. Involve the Smartphone – Don’t forget that the device is connected to a phone that’s close at hand. This cuts two ways: Smartphone apps can extend to Glass so the phone can go back in the pocket, and Glass apps can invoke counterparts on the phone. The two can even be used in tandem, unlike a phone and tablet.
5. Augmented Reality is a Bitch – It’s a multifaceted technical challenge, and each part is astronomically difficult. On top of this, Glass gets two hours of battery life processing video. Avoid AR, it’s a trap.
6. Don’t Distract the Wearer – Your app will be used while the wearer is doing something else – talking, waiting for a bus, walking to work. Don’t pull them away from their primary task, bug them with notifications, or expect them to give your app full attention.
7. Give Them Something to Share – When a user has Glass and others don’t, it creates an uncomfortable us-versus-them tension. Ease it by giving the wearer things to share with their Glassless friends, and make it easy to use the app for friends’ suggestions.
8. Don’t Allow Creepiness – Don’t videotape people without their permission. Don’t read someone’s Twitter while talking to them. Don’t encourage camera-aided manhunts. Don’t stream porn when it’s inappropriate. If you’re designing an app, have responsibility, class, and taste.