Encircling the grave:
Many have the custom of encircling the grave. The Rebbe would circle the grave one time prior to leaving.
Taking off the shoes:
As a sign of respect it is accustomed to remove the shoes prior to entering into the Rebbe’s Ohel.
Placing a hand on the grave:
Many are accustomed to place a hand on the grave upon praying [see next regarding Hishtatchus]. One is to place specifically his left hand on the grave.
This is the general term used for the Mitzvah of visiting a Tzaddiks grave. It literally means prostrating, as the ideal Mitzvah of being by a Tzaddiks grave is to prostrate oneself over the grave and recite prayer. It is for this reason that many are accustomed to try to at least touch the grave while visiting.
It is customary to recite a compilation of Psalm’s and prayers entitled “Maanah Lashon” upon visiting a gravesite of a Tzaddik. There exist various dialects of this compilation. The Chabad Nussach of Maaneh Lashon was compiled by Rabbi Dov Ber of Lubavitch, known as the Mittler Rebbe, on occasion of his visits to the burial site of his father, Rabbi Shnear Zalman of Liadi, in Haditch. This Maaneh Lashon was reprinted by the Rebbe in the year 1950 shortly after the Histalkus of his father in-law, the Rebbe Rayatz.
Placing a stone on the grave:
Many have a custom to place a stone on the grave prior to leaving. The reason behind this custom is to leave a sign that one had visited the grave, out of respect for the dead. [It was never witnessed that the Rebbe placed a stone on a Kever.]
 M”A 581/16; Aguda; Shlah 213; Kneses Hagedola 581/10; Mateh Moshe 789; Kaf Hachaim 581/92; M”B 581/27
 This is based on a story of a woman who once had a sick child and encircled the Azara and he recovered. [Aguda ibid]
 Birkeiy Yosef 224/7; Kitzur SHU”A 128/13; See Sheiris Yehuda Miluim 35 that the custom of Hishtatchus is to actually touch or lean on the grave.
 Minchas Elazar 1/64 based on Kisvei Arizal; Sheiris Yehuda ibid
 Sefer Haminhagim p. 117 [English]
 The “Maaneh Lashon” is mentioned in numerous Poskim. [See Beis Lechem Yehuda 391/7; Peri Megadim 581 A”A 16; Lechem Hapanim 376] The earliest printed Maaneh Lashon that I have found was published in 1627 and can be found on  One can download a PDF of the Chabad Maaneh Lashon [Kehos 2000] at: www.hebrewbooks.org/15693
 Drashos Mahrash [teacher of Mahril]; Eliya Raba 224/7; Kitzur Shlah Miseches Rosh Hashana; Kaf Hachaim 581/92
 Hiskashrus 884