Each platform has its own ecosystem. Then Upwork is not as Freelancer and is not as Fiver.
The way is using each platform according to the purpose of their services.
I think the best rule is to show in the proposal exactly how you will solve the client issue or problem. Not talks about yourself but about how will you do the work.
Another problem with Upwork is that posting jobs is totally free. Then you should analyze the client before making a proposal. As you normally will have only 30 proposals each month and clients can make infinite job offers.
Then knowing how to find the clients that match you is critical.
I created a series of 8 videos (up to now I published 6) that give more details about these kinds of advice. On they, I mention my own experience and not what I read on other internet sources. It’s a good complement for the general readings. They are in Spanish but translated into English (captions)
Cómo tener éxito trabajando desde casa en Upwork? – YouTube
I also mention tools to get the job offers faster.