Dont just use prompts.
Prompts are basic level beginner stuff.
Instead, consider using custom instructions inside your profile. Managing your memory. Project instructions. Source files. Google drive reference files.
User input - GPT custom Instructions - GPT memory - GPT Project Instructions - GPT source file - GPT google drive - GPT output
This way you can insert your prompts at specific points in the chain. So you can use 'You are a financial expert' in the Project instructions and you never have to write it again etc