Since we make the Sign of the Cross before and after our prayers, many Catholics don't realize that the Sign of the Cross is a prayer itself. It should be said with reverence; we shouldn't rush through it on the way to the next prayer.
Using your right hand, you should touch your forehead at the mention of the Father; the lower middle of your chest at the mention of the Son; and the left shoulder on the word "Holy" and the right shoulder on the word "Spirit."
Eastern Christians, both Catholic and Orthodox, reverse the order, touching their right shoulder on the word "Holy" and their left shoulder on the word "Spirit."
The Sign of the Cross
In the name of the Father, and of the Son, and of the Holy Spirit. Amen.