10:4 Tefillin are put on while standing. A person must reach into the bag and remove his tefillin; one may not shake the tefillin from their bag, as this is considered acting disrespectfully towards the mitzvah. The tefillin are first placed on the arm and the blessing l’haniach tefillin, that God commanded us to don the tefillin, is recited. [The letter hei of l’haniach is pronounced with a kamatz, pronounced “aw” in Ashkenazic Hebrew – and the lamed of tefillin has a dagesh, indicating that it is doubled, i.e., tefil-lin.] After this blessing is recited, the knot is tightened on the arm and the strap is wrapped around the arm seven times. (If one accidentally tightened it first, he can still recite the blessing after – see Mishnah Brurah 25:26.) Next, a person places the tefillin on his head and recites the blessing “al mitzvas tefillin,” that God commanded us regarding the mitzvah of tefillin. After adjusting the head strap, the person continues with “Baruch sheim kavod malchuso l’olam vo’ed” (Blessed be the Name of He Whose glorious kingdom lasts forever – see 6:4) because there is some doubt as to the need for a second blessing on tefillin. This doubt also raises the question of whether or not someone who hears the blessing “al mitzvas tefillin” should respond with “Amen,” so the Kitzur Shulchan Aruch recommends that this blessing be recited quietly. After adjusting the tefillin on the head, a person wraps the strap around his hand, thrice on the middle finger, once around the middle joint of the hand (by the fingers) and twice around the lower joint (by the thumb).
10:5 If a person happened to remove the head tefillin from the bag first, he must pass by fulfilling this mitzvah, covering the head tefillin and donning the arm tefillin first. The Torah gives precedence to the arm tefillin when it says, “bind them for a sign on your hand and let them serve as frontlets between your eyes” (Deut. 6:8). Therefore, one must pass by the mitzvah of the head tefillin, even though we normally perform mitzvos as they come to us. (If one happens to put on the head tefillin first, he should leave them on and hurry to put on his arm tefillin – see Mishnah Brurah 25:22.)