Most of the time you're not going to have to worry about cause, whether it exists or not. About the only time cause matters is when there is a conclusion that either says or implies that A causes B. When that happens, you just have to check for a cause/correlation flaw, e.g., "People who eat 3oz of almonds per day tend to be thinner than people who don't, therefore almonds contribute to weight loss." Even in this example, you don't have to know whether the relationship is actually causal. The fact that the premise does not explicitly indicate cause is good enough to spot the flaw. Other than that kind of argument, you are unlikely to have to deal with causation vs. sufficiency.
So what I do is simply ignore the possibility of causation altogether and treat everything as a simple conditional, asking only, "what do I know?"
Consider two statements:
good grades --> study
bullet to the brain --> death
The left is sufficient, and the right is necessary. I don't care that one of these statements is causal and the other is not. It doesn't matter (unless an argument draws a conclusion as in the example above). I treat them both as if they were the same type of statement:
If someone has good grades, what do I know? They studied. Good grades are sufficient to know there was study.
If someone has a bullet to the brain, I know they're meeting with death. Bullet to the brain is sufficient to know there is/was/will be death.