Start on the medium preset (or if the game defaults to optimized settings, leave it that way), turn on the performance overlay, and then just play for a while, so you can get a sense of the performance including different scenes and environments. See where you’re settling FPS wise. Is it hovering around 30, 40, 60, etc? Also note the frame time graph. Is it smooth, or is it jumping all over the place? Set the FPS limit (either in game or via the QaM) to the FPS that it’s hitting most around. Play for a bit again and note the frame time graph. Has it smoothed out now, or is it still spiking?

If it’s flat or mostly flat, you’re either done, or you can try upping the quality a bit. Change one setting at a time, at first to see what effect it has. Some setting might have an outsized performance cost for the improvement to quality. If it tanks your performance, you probably want to go back. If the performance is relatively unaffected, see if you notice anything visual improvement. No sense of going higher, even if the performance cost is minimal, if you can’t notice a significant difference. If it noticeably improves the image and doesn’t cost much leave it at the new setting and move on. Rinse and repeat.

If, instead, the frame time graph is still spiking, you can reduce the frame rate more, or opt to reduce some quality settings. The method is similar to the above, but here, you’re essentially working in reverse: trying to find settings improve performance dramatically, while having negligible impact on visuals. Something may greatly improve performance but also make the game look awful when lowered, don’t drop those unless you eventually find you have to just to get the game playable.

Eventually, this will all sort of become second nature. Once you start to see patterns in how various settings impact both the performance and visual quality in games, you’ll know instinctively what to go change and how. The process is detailed is more intensive, but will help you start to understand what each of the settings does.