Often it will be useful, in selecting a remedy, harvesting in the wild, or attempting to diagnose the nature of an imbalance, to avail yourself of dowsing techniques. The basis of dowsing, in a nutshell (it is, in fact, a highly complex art that merits a lifetime of study in and of itself), is that the Vital Force, in whatever specific essence it may be embodying, can cause a system which is otherwise completely random to take on the characteristics of that essence as it flows through the system. What this means is that randomness in, say, the motion of a pendulum; or the arrangement of a deck of cards; or the casting and grouping of
Yarrow stalks, is affected by the ‘flavor of the moment’: by the specific essence that is coursing through everything at that specific time and place. This is the first important part of any dowsing technique: the random system. The second part, which is just as essential (if not more so), is the connection that is established between what we are dowsing and the system we are using to interpret the ‘flavor of the moment’. This means that merely setting randomness into motion won’t do much of anything: you need to link your random system with what you are dowsing for, creating a correspondence between the two. Remember how the Vital Force flows through similar / related pieces of the natural world? The goal of establishing an energetic link of similarity desired essence to flow through the random system and thereby reveal itself a bit. The easiest way to do this is by using your mind as the conduit, and simply focusing strongly on the object / plant / person / place you are dowsing, and refining that focus by asking a simple question that defines what you want to know.
One of the simplest dowsing tools is the pendulum. It has the advantage of being highly portable, and dealing very well with concrete, tangible things. It is slightly less effective (or rather, consistent results are a bit harder to achieve) with abstract concepts; something like the Tarot or the I Ching works better in the latter cases. The disadvantage of the pendulum is that it can give only one of three answers: yes, no, or maybe. But when artfully used, it can help narrow down a list of remedies for a client, or aid in determining what might be amiss.
At its simplest, a pendulum consists of a weight attached to a string or chain. It can be anything: improvised pendulums made of twine and trailside stones can be just as good as elaborate enchanted pieces. However, the more special your pendulum is to you, and the more often you use it, the more reliable the results (again, because more layers of personal meaning and connection are brought into play). In general, the heavier the weight and the lighter the string, the faster your answer will come. The tradeoff is more inaccurate results.
If you are willing to be more patient, you will often get a more accurate (and definite) answer, since the pendulum can start off one way before easing into its final movement. I use a weight made of silver and quartz (not too heavy), attached to a pretty sturdy cord.
Sometimes I have to wait more than five minutes to get a clear answer.

Hold the pendulum over whatever you are dowsing and, with your mind clearly focused, repeat the question (aloud or silent). Sometimes it can help to ground and center yourself before beginning, to help rid yourself of outside influences. After some time, the pendulum should begin to move. Stay focused on the object and the question, and keep at it until the pendulum settles into a definite motion that you feel confident represents the answer to your question.
To get a final ‘yes’ or ‘no’, you have to be able to interpret the motion of the pendulum. There is no ‘right’ way to interpret it, and I have found that the swings for ‘yes’ vary widely from person to person: some say side-to-side, others say clockwise rotation, others say counterclockwise rotation. The easiest way is to start by asking the pendulum an obvious question, one that you know the answer to already, and see how it responds to you: for example, I would ask “Is my name Guido?” or “Is the sun shining right now?” Ask a few of these questions, and be patient as you attune yourself to your new tool. You will start to notice what swing is ‘yes’ for you, and what swing is ‘no’. After you can get consistent results on the obvious questions, you are ready to use your pendulum for those queries whose answers you don’t know!