The shadow you choose is the darkest one with details that matter for your shot. To verify whether one shadow is darker than another you use your spot meter to determine relative reflectivity.
Honestly i do not feel it’s that complicated, at least for the goal of getting started. I totally respect that others approach exposure as a complex process and I’m not deriding that approach. But I also think folks who are new to film, as the OP obviously is, need advice that builds confidence and is not overwhelming. And to that end I’d rather try to simplify the process.
It’s the same with film stocks & developers. The best advice is just pick one stock, one developer, one process, and stick with it for a year or whatever. Does that mean it’s the best possible combination of film & developer. No. But is it good enough until the photographer builds experience and grows out of it? Yes. Will they better understand the materials and how to work with them as a result? Yes.
Honestly i do not feel it’s that complicated, at least for the goal of getting started. I totally respect that others approach exposure as a complex process and I’m not deriding that approach. But I also think folks who are new to film, as the OP obviously is, need advice that builds confidence and is not overwhelming. And to that end I’d rather try to simplify the process.
It’s the same with film stocks & developers. The best advice is just pick one stock, one developer, one process, and stick with it for a year or whatever. Does that mean it’s the best possible combination of film & developer. No. But is it good enough until the photographer builds experience and grows out of it? Yes. Will they better understand the materials and how to work with them as a result? Yes.

