Having someone else study you for tells

[beekeeper]

I'm returning to a game that's been on hiatus. I have a friend who also plays in that game. We talk a lot about the game. If one of us sees a tell on the other, we'll tell the other after the game. I'm thinking about asking this friend to observe me for about 3 weeks (3 tourneys) for tells--I'll do the same for him if he's interested. Based on what Harrington said about the hands being a more reliable tell, should I ask my friend to focus on what I do with my hands?

Also, I've been trying to watch for tells related to hands, but I'm not picking anything up. Does anyone know what I should be looking for?

Thanks in advance.