All of this is good advice. For me, I also think, “What zines do I like to read?” I like per-zines, so I make per-zines. i like stories about sex, so I write stories about sex. Same thing in my band, I try to make music that I’d want to go see.
All that being said, at some point you just have to do it. Once your first issue is out, you’ll see stuff you like and stuff you don’t, then you’ll improve by the second issue. Every issue of a zine should be better than the one before it, that’s part of the long-term process, it’s not a bad thing.