Awareness of the whole body, keeping it relaxed, contemplating its impermanence and the illusory nature of the mind
From Meditation guideAbout 1 min read

Once you are sitting correctly, the next three things are to be aware of the whole body, to keep the body soft yet still, and then to contemplate the body and the mind.
Being clearly aware of the whole body
Check whether the back, shoulders, head, hands and eyes are out of position, and correct them at once. Be aware gently, without forcing. Pay most attention to the lower abdomen, the two legs and the palms of the hands.
Keeping the body soft and still
Do not move, but do not stiffen either. When you notice the muscles tightening by themselves, release them at once.
When wandering thoughts or drowsiness arise
When wandering thoughts arise, simply return to awareness of the whole body; there is no need to try to wipe them out. If you feel drowsy, first look at your sleep, your level of tiredness and your alertness. The Teacher holds that if these factors are normal and yet wandering thoughts or sluggishness persist, you should recite the Buddha's name and repent.
Contemplating the impermanence of the body
For a few minutes at a time, see that this body will in time break apart, from the time it is alive until it turns to ashes and dust. The Teacher says it takes a few months of training to become proficient in this contemplation.
Contemplating the illusory nature of the mind
Recognise that every thought, good or bad, is not real, and let it go; the mind will then settle and become clear. The Teacher stresses that this does not mean "do no good and do no evil": you must still put an end to evil and do much good.