Proper intentions in Miswot:

Before one preforms a Miswa, he should always say Leshem Yihud. Rabenu Hayim Palagi, recommends that we read in the Zohar, where it talks about the deed we are about to preform. He gives an alternative, that you may just read in the Humash where it speaks about that deed. This is what Rabbi Shneur Zalman used to do (Kaf HaHaim 1:3).