Tefillin are worn every weekday. This means that on Shabbat, Holidays, and the intermediate days (chol hamoed), tefillin are not donned.
The tefillin shel yad (hand tefillin) should be removed first from the tefillin bag. If you first removed the tefillin shel rosh (head tefillin), put it aside, and remove the tefillin shel yad.
It is customary to kiss the tefillin when they are taken out and when they are put back.
Care must be taken that there be nothing intervening between the tefillin and the flesh. Watches should be removed from the wrist and rings from the fingers. When a long-sleeved shirt is worn, make sure that no part of the shirt is caught under the tefillin. The same is true of the head tefillin, where one has to ensure the strap is resting on the head and not on the yarmulka. If you have a bandage on the arm or head, consult a Rabbi as to what to do.
After placing the tefillin on the biceps, and before tightening the straps, the blessing l’honiach tefillin is recited. There must be no interruption between putting on the hand-tefillin and the head-tefillin. While reciting the blessing, intend that it apply also to the head tefillin.
It is customary that both the blessing and the actual laying of the tefillin be completed standing.
The head tefillin should be placed so that they lie exactly in the center of the width of the head. The base of the tefillin should be just above the natural hairline.
Care should be taken to ensure that on both the tefillin shel yad and shel rosh, the straps' black side is showing.
It is prohibited to enter a bathroom wearing tefillin.