Let me ask you a question. Would you let a dentist perform brain surgery on you?
Would you let someone who has never cut hair, do your hair?
The reality of the world is nobody wants to hire someone who hasn’t done it before. Yes, that sucks for you if you are just starting out.
In the relevant experience section of your proposal, you’ll list the experience that proves you can do it. You might have to get creative with how you describe that experience, but always be truthful.
Describe what you’ve done for other clients just like them. Five relevant projects should be plenty. If you have three relevant projects and two that are stretch, just use three. But ultimately, you should have at least one.
If you can, add photos and contact information for your previous clients.