By Brian O’Connell Black Friday is only days away. Here’s how to avoid any “trap doors” when holiday shopping. The worst kept secret in retail is that Black Friday shopping deals start the day after Thanksgiving. No, not really. Retailers now routinely roll out big discounts – they even call them “Black Friday” discounts – well ahead of Thanksgiving weekend. Consider Walmart, which promotedits first Black Friday sales event from Nov. 7 to Nov. 9, featuring an HP Chromebook for $79 and a TCL 55″ Class 4K Smart Roku TV for just $188. “Other big box stores including Lowes, Target and Kohls droppe…