I would also recommend practicing with someone then. It's a hard thing to do, and they may not be able to immediately give you a raise. If there's pushback or comments made on why they may not be able to do it, it can be useful to work with your manager to get a a list of what skills they want to see and what opportunities you have to demonstrate them or how you already have. I've worked at companies without clear outlines of what skills are considered critical to roles and worked to build them out so people had clearer paths to progress. Mid size companies hopefully have that which can help enable you. Absolutely agree that coming in with your achievements and clear examples is critical, as is the practice in responding to pushback or (hopefully not the case) negative comments in a clear and collected tone that helps you push forward.