At the end of three weeks, we should go to Confession and Holy Communion with the intention of giving ourselves to Jesus Christ in the quality of slaves of love, by the hands of Mary.
After Communion, we should recite the Act of Consecration http://www.francismary.org/act-of-consecration/ ; we ought to write it, or have it written, and sign it the same day the consecration is made.
It would be well that on this day, we should pay some tribute to Jesus Christ and our Blessed Lady, either as a penance for our past unfaithfulness to the vows of Baptism, or as a testimony of dependence on the dominion of Jesus and Mary.
This tribute should be one in accordance with your fervor, such as a fast, a mortification or an alms, or a candle. If but a pin is given in homage, and given with a good heart, it will be enough for Jesus, Who loves only the good will.
Once a year at least, and on the same day, we should renew this consecration, observing the same practices during the three weeks.