Here are some extemporaneous tips and pet peaves regarding herbs.
* Herbs loose potency on drying, and sometimes their constituents not only degrade, but change into other things. Powdering herbs should only be done before use or extraction as the vast surface area exposed in powdering leads to rapid dissipation and degradation of the herb's constituents. If you buy dried herbs, look for ones that look and smell like something that was once alive. Brown-drab near powder with no smell is going to do nothing good for you. Such herb quality also speaks to a general poor handling, and one might be concerned with mold from improperly dried herbs. Very few herbs work well in capsules. Some herbs, like dandylion root, must be used fresh or freeze dried in order to be most effective. Fresh lobelia tincture will calm your nerves and stimulate your parasimpathetic nervous system. Dried lobelia will make you puke.
* If you want to make herbal oils and salves, don't stir them around in a double boiler. It makes the herb gods angry. Instead use the intermediary solvent extraction method which goes thusly: For every ounce of herb use 7 ounces of olive oil and 1/2 ounce of pure ethanol (95% counts as pure because if you open pure ethanol it will absorb water from the air). Grind the herb to a fine powder in a blender, taking care not to scorch. A chunk of dry ice in the blender can help with this, as can freezing the blender and herb beforehand. (Courtesy Adam Seller) Dump the powdered herb in a sealable container and moisten with 1/2 part ethanol (so if you have 3 ounces of herb, that's 1.5 oz ethanol). Leave overnight to macerate. Next day dump in blender with 7 parts olive oil and blend the hell out of it for like 15 minutes until the sides are warm but not hot. You are now done. Strain and bottle or melt with beeswax to make salve. The reason this is vastly superior to the double boiler method is because the alcohol disolves the herb overnight, and then the blades of the blender spinning the herb through the oil strips it all off. In a double boiler you're relying on heat. Here you're relying on kinetics and an intermediary solvent. Oils done this way come out green and fresh smelling as opposed to toasted smelling and olive oil colored. If your salve or oil is not the color of the plant it claims to represent, it's useless. Oh, it's also much less work than stirring a double boiler for hours.
* Never overlook weeds and common plants. They are often the best medicine. While we are all thrilled about exotics like Devil's Claw (not), who here remembers to drink their nettle tea? Weeds are wonderful because the're abundant, cheap, and easy to harvest. Using the simple medicine is always best. Incorporating herbs into your diet, is preferable to desperately resort to them once you're ill. Sure there are herbs for many dire situations, but it's not their strength. Their strength is in being entirely common, quotidian, homely, and available in quantity.
* Different herbs have different preferred methods of extraction. Tincture of Osha works great, tincture of peppermint is pointless. Osha's hard to get into tea, but peppermint infusion is lovely. When in doubt, consult Michael Moore's Materia Medica for extration methods and ratios.
Southwest School of Botanical Medicine Herb Manuals
* Dose is dependent on many factors including the strength of the herb, drying method, extraction method, how old it is, etc. The common and generally safe herbs have a large range of safe dosages, so if you use too much it will probably just taste strong. Some herbs are very dose dependent like lobelia, pulsatilla, and veratrum. These sorts of herbs should be used only under supervision of someone with a clue. For topical applications, dose is dependent more on time then on concentration.
* Most herbalists are really bad. The discipline seems to attract megalomaniacs looking for easy dupes to milk for cash, people who substitute big words for critical thinking, and people who have an irrational faith in "nature" as a romantic benevolent force. Many will gladly lie to you confidently when they don't know, and will accept clients for diseases they know nothing about. Others will sexually harrass you while talking about energies. Put your bullshit meter on high sensitivity when dealing with alternative practitioners.
* All plants are psychoactive. They all affect your mind if you let them. Tell me a gardenia blossom does not change your consciousness. Tell me staring for 10 minutes at a passion flower will not get you high. Americans tend to have a consumer mindset toward plant drugs and utterly fail to benefit from them. If you're interested in cultivating an intuitive relationship with plants, start by paying attention to the plants around you. Some things are subtle. If you blast your brains with mescaline, you will not hear the quiet ways plants talk to you. If all the house lights are up, you can't see the movie. Quit chasing idiotic highs. The cultures who used drug plants ritually did not just get a bunch of friends together, say a prayer, and trip. There was strategy, and contingencies, and things to do. Do not trivialize halucinogenic cultures by presuming that what you do with drugs bears much in common with what they do.
* If you're interested in Native American culture, don't presume to speak for them, don't rip off their art, technology or beliefs and pass them off as your own, or pass your own off as theirs. Provide tangible material support. Always bring food. Listen more than you speak. Don't presume that people who disagree with you don't understand what you're saying. Remember Native Americans know much more about white culture than we know about them. Don't make Native American people into some romanticized representatives of a tranquil and harmonious past. All that hippie fake Indian shit is offensive and dangerous. Lots of Native kids grow up with a distorted understanding of their own culture because of our illusion making. Ritual is an important but small part of Native cultures. If you read Native news, they spend more time talking about land and water rights, electrification, health issues, domestic violence, and substance abuse. Remember that American herbalism and Permaculture owe Native American cultures a great debt.
I have used it for lungs when infection is involved (Bronchitis, etc.) and kidney stuff (actually UTI) and since it is also antifungal, it works very well with yeast infections, better than other things I have tried in the past. And you really don't need many drops in a dose (and as mentioned, you may not want to)!