1) On the eve of Rosh Hashanah one must cut one’s hair and make sure that one’s clothes are washed in honor of the festival. On Rosh Hashanah one wears clothes of Shabbos to show that we are confident to receive kindness from Hashem, and that he will bring our judgment towards light. (Kitzur Shulchan Aruch 129)
2) Some have the custom to visit graves of righteous people on the eve of Rosh Hashanah and when they are there they give charity to poor people and request from Hashem that He will listen to their prayers in the merit of the righteous people buried there, or that the righteous people themselves should pray for them before Hashem. However, one must be extremely careful not to put his faith in the dead people who rest there, because that comes very close to the sin of “Seeking from the dead”. (ibid)
