1. After the Shemoneh Esreh, one recites prayers of supplication, referred
to as Tachanun while "falling on one's face;" [i.e., leaning downward and
covering one's face with one's arm]. It is improper to talk about mundane
matters between the Shemoneh Esreh and Tachanun.
2. In the morning service, because of the tefillin worn on the left arm,
one leans to the right out of respect for the tefillin. In the afternoon
service, one leans to one's left.
3. One should lean and cover one's face while seated. However, under
difficult circumstances, one may do so while standing. After Tachanun, we
recite the passage Va'anachnu lo neda'. Its recitation should be begun
while seated, and at the phrase mah na'aseh, we should rise.