For B&W I set my spot meter to the mfg rated ISO speed, point it at the darkest area where I want texture. The reading is my exposure. When I use auto metering to handle changes in illumination I'll turn the compensation dial until the in-camera meter agrees with my spot meter. I'll also scan the scene with the meter first to choose a film and developer.
When shooting slide film I meter at the ISO speed with the expectation that I will have 2 stops of texture below, and some amount above which depends on the film. For Astia, for example, I expect 2.5 stops of texture above the reading.
Works every time. Like magic.