Here is the favorite old picture of a guardian angel and the favorite old prayer to one's guardian angel, whose feast is today, October 2:
The Guardian Angel Prayer
(in Latin and English)
qui custos es mei,
me tibi commíssum pietáte supérna,
illúmina, custódi, rege et gubérna.
"Angel of God, my guardian dear
to whom God's love commits me here.
Ever this day (or night) be at my side
to light and guard, to rule and guide.
Leiber's "Guardian Angel", from Wikimedia Commons. In the public domain.