The PP who said that homeopathy "treats the whole person" rather than the symptoms has hit the nail on the head. There can in many cases be a strong and measurable clinical effect of having someone listen sympathetically and seriously to your concerns and worries and say that they can help. In recurrent miscarriage, for example, just being referred to a recurrent miscarriage clinic increases the chance of having a baby, without any other intervention.
So for some situations homeopathy may appear to "work" , but it's not the substances that you have been given, which are of no clinical value whatsoever, it's the interpersonal interactions (or that the problem just got better on its own). The big danger comes when people eschew mainstream treatments in cases where this is going to cause them harm. Sometimes this won't matter, lots of things resolve on their own and no harm done by taking tiny sugar pills or sips of water. But some very serious things don't, obviously, even with sympathy and positive thinking.
"Herbal medicine" on the other hand, may have benefits in some cases, and indeed was the foundation of what we now know as pharmacotherapy. Lots of substances found in nature are similar to, or even the original basis of, highly effective modern manufactured medications (salicylic acid, St John's wort, digitalis, etc etc). For example, in some cases where antidepressants are causing problematic side effects St John's wort can be a gentler alternative. It's not as effective an antidepressant of course, but it can be better than nothing (combined, again, with positive interpersonal interactions). In communities where modern medicines are not available, using foxglove in cardiac disease and willow bark tea for pain is going to be better than nothing.