I have found gratitude and appreciation in general to have a benefit in the material world, but I don't really go in for making deals with Goetic demons. But Elubatel remains a mystery to me, because we're apparently dealing with an angel of omnipotence, rather than a demon, so the approach might need to be different.
One solution is to perform NAP exactly as the book states, but I don't think many people here do that. We're all putting in a bit of extra protection, ramping up the energy and so on. As such, we tamper. In doing so, I get to that point in the ritual where I'm addressing Elubatel, and I remain uncertain of the tone to use.
I wonder if perhaps it should be more the way a good manager would issue commands to workers; you don't ask them to do the work, you tell them, but if you're a good manager it feels like a respectful request rather than a harsh order. You say it politely, with the full expectation that your workers will do what they're asked because that's why they are there, and you don't need to offer them anything extra to coerce them into action.
I'll keep experimenting.