Hi Nicolas,
It's hard to get the first job on Upwork for most of the freelancers, I have sent dozens of proposals to get my first job.
If clients do not reply we can think positively like He didn't need quality work as I provide, or maybe the client hired someone else before I'm applying for the job, etc.
while making sure your profile is well prepared with previous works, the right keywords of your profession, and with previous experiences etc.
I hope this helps.
