Negotiations in general
The basis of any adult-to-adult relationship:
able to ask for what you want, knowing that the answer may be No and negotiating the difference.
Start with No
Contract negotiations
https://www.pandadoc.com/blog/how-to-negotiate-a-contract/
Salary negotiations
https://careercutler.substack.com/p/how-you-can-15x-your-salary-through