Faisal,
The problem is often rooted in a misunderstanding of how the process works.
You have to be very careful not to cross the lines. If you cross a line, you can very easily sound too pushy or arrogant or simply make it clear that you do not understand the client's frame of mind.
The mistake that I see is when you said, "even after writing a very detailed and personalized proposal," you don't get responses. That is often where the trouble lies.
If you want to sell something -- like selling a car or a house -- if you go too quickly, you will scare the customer away. It is just like asking a man or a woman for a date. If you go too quickly, you will make them uncomfortable. They will run.
To stay safe, you have to understand the purpose of each of the steps. The proposal letter is ONLY designed to entice someone to look at your profile. That is ALL the proposal letter can do. So, if you overdo it, they will think they are being lead into a trap. You have to be very subtle and sound very safe. You might suggest someone look at your profile, or say "there are writing samples on my profile page," but that is it. You are NOT selling anything in a proposal letter. You are only suggesting they look at your profile. So, be friendly. Do NOT be pushy. Do NOT provide them with a lot of details. Some details might be on your profile page, but I would be very, very cautious about that. Keep details as far away as possible until you actually have a conversation with the clients. Provide no details in proposal letters and very, very few on your profile page.
That said, the ONLY thing that a profile can do is get someone to talk to you. That's it. Do NOT push too hard with your profile. Just leave it there and let people make up their own minds. If your profile says you have what they want, they will move forward and suggest you talk with them.
Again, this is like asking a man or a woman on a date. If you push too early and too fast, you will scare them away.
ONLY when you talk to people can you push for a sale. Not before that. During the early talk with clients, you can give them the details that might be confusing or threatening. NEVER put too many details in your proposal letter and NEVER put too many details on your profile page. The first opportunity you have to provide details is when you and the client are actually talking.
You said you are writing "very detailed" proposal letters. That is a mistake.
When I was writing a lot of proposal letters, I would write three or four very short sentences. I had very good results. My confidence went up, so I started writing longer paragraphs -- and guess what happened. My results got worse.
Do NOT say too much too early. A proposal letter is just to get people to get curious about you -- curious enough to look at your profile. A profile is just to get them more curious -- curious enough to invite you to talk with them. That's it. Not until you talk to people can you provide details. Keep that very low key until the opportune time.
Good luck.
