You don't need to overthink this. Here's what helps:
Lighting: Film near a window or go outside. Natural light makes everything look better.
Sound: Pick a quiet-ish spot. It doesn't have to be silent, just avoid blenders and barking dogs.
Eye contact: When speaking, look at the camera lens, not yourself on the screen.
One take is great: Seriously. We love the real, unpolished stuff. Don't re-record ten times.
We can edit and splice your footage so don't feel like you need to perfect it. One long take with mistakes and do-overs are fine.