Doing something is almost always better than doing nothing
But doing anything is not often as good as doing something.
Just about anything you do to encourage and care for a missionary will be helpful. Doing something that includes an understanding of their needs is even better.
Many people assume that they are unqualified to offer care, or that they don’t have anything of value to offer. While such assumptions are almost certainly wrong, it might be better to not try and step in when you don’t know what you’re doing.
On the other hand, what if the assumptions are wrong? What happens if you do nothing?