#1 - Lighting is everything. Key light front and to the side, room light off, background light behind and on the opposite side. Maybe get these or something cheaper and simpler. This is the way things are now.
#2 - I don't know why, but it takes effort to look worse and more unprofessional then Eric Yuan, the actual CEO of Zoom. Maybe it's intentional. I don't get it. Either way, that's the low bar, just stay over it.