I got this from an excellent book called Managing Up by Melody Wilding:

There’s a whole chapter on how to ask for a raise, and I really like it. Here are a couple of extracts – but get the book!
Preparing the ground

… and there’s lots more in the book than this!!
..
Actually asking

..
Negotiating a good amount:
Get this course, chapter 1 is all about specifically how to negotiate for a raise https://www.udemy.com/course/negotiation-practical/ – and it will pay for itself immediately, not just on pay rises but on everything else!
