How do you write a proposal on UpWork or freelancing in general is there a framework or a book you recommend?

I am completely new to freelancing and want to sell programming more specifically AI related services with LLM integrations and multi modle applications with langchain. And I see that there is a market for that but I don't know how to sell my service. The only thing I know is that what I can is irrelevant since it only matters what the customer wants but how can I brighe that gap. Is there a course or book on sales you recommend or should I just start making proposals all day?

Its always best to take some course before simply making proposals, Noways there is tough competitions.

Recently I purchase this for fiver from udemy https://www.udemy.com/course/fiverrsuccessguide/learn/lecture/3026150?start=0#overview

but There is some tutorials available for Upwork and freelancers on Udemy

Honestly, im sure you could chatgpt something up. Make sure to make it sound short and sweet though, as it likes to give long paragraphs. Tell it details and it'll do well