Assuming I'm not misunderstanding Ferounius' post, I have to agree. Some people try to level multiple crafts at once, which can be a huge pain.
The easiest way to do it, is to take it slow, and not try to power through to a high crafting level at once. For herbalism, I gather the occasional herb, and make the occasional potion.
While this may take a while to get to a higher level, the PC's needs aren't abundant, and it works well enough. I don't spend huge amounts of gold in one go, nor do I have tons of herbs in my bags.