 It's back. And while some early prime deals are available, the main two-day event starts tomorrow at 3 in the morning. Your first tip when you choose a deal, make sure it's really won by using the site camelcamelcamel.com or the Keepa app. That's K-E-E-P-A. Both follow Amazon item prices like stock charts. Also check other major retailers because they may be competing with deals of their own.