What did Client's see before they hire?

[#1]

I have a question to clients? 

What they see in a new freelancer specially in social media marketing, that they can hire ??

A review, projects completed or Earning. 

And if a new freelancer have nothing like me, who don't get chance to prove on this platform what should they do now?

[#2]

Hi Shivang,
I hope you're doing good.
This is the screen that how client see our proposals for his job post.

I hope this would help.
Thank you
Regards,
Aine