Some communities have the custom to visit gravesites on Erev Yom Kippur in order to increase in charity while there. This is a good custom. The charity that is given by the cemetery is the worth of the chickens used for Kapparos, known as Pidyon Kaparos. It is therefore proper to give charity in correspondence to the amount of Kaparos he used for his family. [This practice was not witnessed amongst the Chabad Rabbeim and is not the custom of Anash.]
Supplications while at the cemetery: One is not to say any supplication [while at the cemetery] other than that which was established by our forbearers, as one does not say Tachanun on this day.
The difference of Avoda between the morning and afternoon of Erev Yom Kippur:
On Erev Yom Kippur in Lubavitch there was a difference between the atmosphere of the first half of the day and the second half, as if they were two completely different times of the year.
 Admur 605/5; Rama 605/1 in name of Maharil
 See Otzer Minhagei Chabad p. 184
 Admur ibid; M”A 605/5
 Likkutei Dibburim 1 p. 184-186 [Hebrew]