At the end of the day, if you abide by all these bits of advice, and I hope you do, you will still have to submit many more proposals than you are awarded jobs for. It’s a numbers game. At the beginning, you will be rejected more than you are accepted. Dust off your ego and get on with it.
When I first started my career as a freelancer, I promised myself I would submit two proposals a day. And I did. Twenty days later, this meant I had quite a lot of proposals out there. Eventually it paid off.
I never worried about all my proposals getting awarded at once; it didn’t work that way for me. You may swing between way too much work and not enough, but over time you will find the balance. At the start, ya gotta hustle.