Flashes are great for interior – but there is something that really makes photos pop. Ambient layer masking is when you take a longer exposure (no flash) with the intention to lighten the photo and ease harsh shadows in Photoshop. Typically, the windows and lights are blown out but we’re concerned with the walls and ambient shadows. Once you have the flash and/or HDR shot of the interior edited, bring it and the color corrected ambient shot into Photoshop as layers. Then create an inverted (option) layer mask and use a 0% hardness brush with a 3% flow and brighten the harsh shadows while adding smooth ones to the obvious flashed areas. There are some great videos that demonstrate this – I would recommend Rich Baum on Youtube. Good luck and happy shooting!