if you keep submitting proposals to many jobs and it’s being ignored or even declined, you should look into that picture, this is what the client sees from his side.
take a closer look and imagine you are in the client’s shoes, you only have 2 sentences to impress me to open your proposal, no matter your skills, even though you could be the highest qualified candidate, but if you write the wrong words at the beginning of the proposal, the client won’t even open it.
don’t start with something like: “hi my name is ….” or “hey I live in X and I do Y…” or even the worst “I’m new at upwork…”
start by presenting the solution to the real problem and show a mind map of how you will solve or do the job.
show the client that you read his description very well and you can start ASAP, I remember I got one of my client’s attention by saying “what a well-written description of a deep technical job”.
once you get his attention by the proposal opening, start asking the right questions, how will you communicate with the team if any? what are the milestones and deadlines required, and so on
finally, take into your consideration that the client might be a developer or even more but he can’t find enough time to do that task and asking for your fast & high-quality input without asking much on something you can find out by yourself