How do I catch subtle signs a patient is getting worse?

The vitals and the checklist give you the numbers, and you handle those well. The quiet decline you are worried about often shows up somewhere the checklist does not look: in how a person seems compared to an hour ago. That comparison is a skill, and it is learnable. The people who catch these things are watching for change, not just readings. A patient a little more tired, a little more confused, a little less themselves. Those soft shifts matter as much as any number, and you notice them by looking at the person, not only the chart. Start building this habit: each time you see a patient, take two seconds to note how they seem, and compare it to last time. Better, same, or worse. That one question, asked again and again, trains the eye you are afraid you lack. You are not missing a talent. You are early in learning to see.