There is much to write on this subject, but this is one of the best resources so have a look here for info on various herbs, uses, contraindications etc. It’s an info site put together by some very well-respected herbalists who really know their stuff:
Next, where to buy good quality herbs? Obviously, for specialist concoctions, you must always see a herbalist trained to make them. However, there are some good companies who make some good single herb and mixed products too.
My favourites here are SHS, Herbs of Grace and the essences from Jan De Vries. Although, there are many companies who do really good herb products within their ranges. Those are just good specialist herbal products suppliers I like.
Whilst we’re at it, we musn’t forget essential oils – a herbal medicine in its own right. I went on to train in this as my first ever therapy. Good stuff. I like Materia Aromatica, Aqua Oleum and NHR ranges best here.
Hope that helps to start you off. Don’t forget to check the various condition-specific pages in this A-Z either as I probably mention helpful things there.