When feeling into subtlety, there are no insignificant sensations. Whatever feeling you focus upon can be used as an entryway to deeper and deeper levels of nuanced awareness. Choose any sensation…tingling in the hands or feet, giddiness in the pit of the stomach, pain in the shoulders, sensations of the incoming and outgoing breath, etc.
The idea here is to focus inwardly on the overall sensation of whatever you tune into. This can also be done with emotions: anger, sadness, loneliness, etc. With any emotion there is a corresponding sensation/vibration that can be tracked in the body.
As you focus on sensations, at some point you may find an expansion of awareness that includes an underlying vibration (like a hum or buzzing) that, in the beginning, is relaxing and somewhat hypnotic.
It is at this stage that the mind and thought processes are settling down and you may experience short periods of detached noticing, as well as periods of “no-thought.” When done with deep focus, this is by no means a “ho-hum” or boring experience, but rather one that imparts a sense of enchantment and even exaltation.