I've learned some of these lessons the hard way. I'll add a few. Proof of work is important, but it's not about the magnitude of energy you spend. I went through two iterations of reaching out to my college network. The first time I put so much time into handwriting notes and trying to provide my relatable background. 100 notes, not a single response.
The second time I sent emails that were a few sentences. I had a much clearer ask and devoted the effort into fitting my questions into the email. I wanted a conversation really, but I also tried to communicate what I planned to ask.
15% response rate and invaluable conversations. Less overall "work".
Secondly, and relatedly, don't ever waste someone's time. Don't ask for / accept a meeting if you don't have some semblance of a clear ask. It's hard, especially in early stage business where you're trying to discover what you don't know. But you can try to lay out your tier 1 "here's what I think", "here are the follow ups".
I sensed once that I had irritated someone by lacking the agenda. Another time I took a mutual connection up on an intro where I didn't know what I really needed. I regret both of these.
Thirdly try to pay it forward. It won't always come back around, but you can feel more comfortable asking for help and more cognizant of what a helper (so to speak) is thinking