Sometimes it is possible to read the description of the usage of an essence and to understand, or know intuitively, that it is needed. If this works for you, use it. However, because of the subtle levels of energy in which these essences operate, it is often advisable to consult your subconscious or Higher Self and to test for the essences required with a pendulum (dowsing) or with muscle testing (kinesiology). In current times, it is crucial that we, as individuals, empower ourselves which is why we recommend that you take personal responsibility for determining which essences you need. Take back your power, use the methods given below and trust yourself.
There is a simple method of using your fingers for muscle testing whereby you link the tip of your little finger and the tip of your thumb on your non-dominant hand. Then link the thumb and index finger on your dominant hand and insert them into the circle made by the fingers of the other hand. To test, ask a question and try to break the circuit of your thumb and little finger by pushing the thumb and index finger apart. The circuit will hold for a positive answer and break for a negative answer. Experiment by asking questions to which you know the answers.
These are very straightforward and effective methods and simply require that you ask for the information, then trust the response. Practice makes perfect!