But I try to get it right in manuscripts. And I’ve even had experiences where editors have tried to correct something I did right by inserting incorrect edits with regard to the subjunctive mood.
It’s basic En101. Here’s a link where it’s explained very well.
And here are a few examples that make it so easy you’ll never have to wonder about subjunctive mood again.
If I were you, then I would not do that.
I am not you, however, so I use the subjunctive to express this hypothetical or counterfactual condition. Especially note that the modern usage If I was you is completely incorrect.
If only she were here, then she would speak up.
She is not here, however, so the subjunctive expresses that fact appropriately. Again, If only she was has drifted into modern usage and should be avoided.
We should act as if he were watching.
We doubt that he is watching or know that he is not.
It is as though she were here.
We know she is not here, but it seems so.
As stated above, these mistakes have “drifted into modern usage.” And I know plenty who would argue the point. But it’s important to know the difference.
There are more examples here.