1) One who says the Selichos by himself, may not say the thirteen attributes of Hashem as a prayer or supplication. He may, however, recite them as if reading in the Torah with the correct tune. A person praying by himself should also omit ny place which mentions the thirteen attributes (e.g. “remember for us today the covenant of the thirteen”). (Kitzur Shulchan Aruch 128)
2) Some say that those supplications written in Aramaic must be omitted by one who prays by himself (ibid), and others contend that he may say them (Kaf Hachaim 581:26)