To summarize, the author touches on 3 mistakes that Dany has been making and I agree with them:

1. She can't connect: One of the key things to do in any negotiation is to set the right tone: "Make sure the tenor is nice and relaxed. The last thing you want is a defensiveness." That's what allows you to connect, he says.
2. She forgets "show, don't tell": Bringing a helpful prop, or even a gift, demonstrates your seriousness in a way that simply talking does not. That's partly why Euron Greyjoy of the Iron Islands has so much more success with Cersei in this episode than he did earlier in the season: Now he presents her with valuable captives, not merely with promises.
3. She has only one goal: Although each of them is clear about what they want to get out of the negotiation, they box themselves in by asking for only one thing.

Interesting post!