It's always seemed odd to me when someone gave instructions like: "here's how to hold your hands while presenting" because for different people saying different things, that pose could look really strange, inauthentic, staged, and entirely misaligned with them and their message.
The best way to align your body language -- and any other aspect of your non-verbal communication -- with your words?
Actually be truthful. Authentic. Present. Then your verbal and non-verbal align naturally.
You tell 'em, Prof. Amy Cuddy! https://www.youtube.com/watch?v=SG5dmLAyCkg&feature=youtu.be
https://www.amycuddy.com/ (Do you know her great book Presence - Bringing your Boldest Self to your Biggest Challenges ? )