Padre Pio, during his lifetime, had a beautiful relationship with his guardian angel; often he would send his angel on errands as described in his biography - we could learn a lot from this relationship.
“Have great devotion … to this good angel. How consoling it is to know that near us is a spirit who, from cradle to the tomb, does not leave us even for an instant, not even when we dare to sin. And this heavenly spirit guides us and protects us as a friend, a brother/sister. But it is extremely consoling to know that this angel prays without ceasing for us; offers to God all our good actions, our thoughts, our desires, if they are pure. Do not forget this invisible companion, always present, always ready to listen to us and even more, ready to console us … Always keep your angel present to your mind’s eye. Often remember the presence of this angel. Thank your angel, pray to your angle, keep your angel good company. Open yourself up to your angel and confide your suffering to your angel. Have a constant fear of offending the purity of your angel's gaze … Turn to your angel in times of supreme anxiety and you will experience beneficial help. Never say that you are alone in sustaining the battle against our enemies. Never say you have nobody to whom you can open up and confide. You would do this heavenly messenger a grave wrong.”
A good way to thank your angel for the support received is to take your angel to the Adoration Chapel. Your Guardian Angel is always with you, so it stands that if you visit the Chapel, your angel too is in the presence of God in a very special way. I have to believe that that favor received by your angel is returned to you a hundred fold.