This may sound weird but it's easier to do this when you don't need it. When we're negotiating, people can smell desperation. If you can easily walk away from a negotiation/offer, you're suddenly in a much more powerful position.
Once you're there, figure out how much sounds like a lot and ask for even more. Either they'll surprise you and accept the terms, or you will negotiate "down" to the amount that sounded like a lot. Worst case scenario, they don't take the deal and you reject them to go find a new negotiation until you get what you want
Once you're there, figure out how much sounds like a lot and ask for even more. Either they'll surprise you and accept the terms, or you will negotiate "down" to the amount that sounded like a lot. Worst case scenario, they don't take the deal and you reject them to go find a new negotiation until you get what you want