- Visit the Windows Phone App Studio website
- Sign in with your Microsoft account and create a project
- Download the Preview for Developers app on your WP8 handset (click here) and sign in with your MS account
- The phone should detect the WP 8.1 update is available
Before going for it, keep in mind that the update doesn't include Nokia's Windows Phone 8.1 workings - the navigation core and the new imaging SDK. You also won't be able to downgrade to WP8 if you experience problems after the early update, but the Preview app should be pushing fixes to you until WP 8.1 is ready for all. As previously noted, Cortana is only available for US residents, although you are free to change your smartphone's location and use it in exchange for any local functionality you might be trusting upon. Also, custom lock-screen isn't available in the developer preview version. But Action Center is, and for some of you, it might be worth the update on its own.