I bought a Sekonic L-308S to use with vintage/old film cameras that either had broken or unreliable meters (for example: Yashica Mat 124G). Anyway, I realized I don't know how to use it and I certainly am not getting any sort of reliable or predictable results by trial and error. Yes, I do set it in shutter priority mode and have set the ISO (to 400). I know there's an incident mode and reflective mode and I know I can either place the "eye" facing the subject, from the camera's POV or by the subject facing the camera's lens. That gives me four possibilities or modes.

When how do I know which to use and when? Some situations are helpful such as taking a picture from a subject too far to walk to (like a mountain). In that case, I am forced to use reflected mode (pointing toward subject, eye exposed). What would happen, though, if I was pointing the meter at the subject but had the eye covered by the lumisphere?

Can anyone help me out with an easy to understand explanation or guide on how to use a light meter?