It’s important to note that when a Catholic “prays to a saint” they are actually directing their prayer to God and asking the saint to help them by also praying to God for their intention. This is called “intercessory prayer” or asking the saint for their “intercession” or their “help”.
It’s like if you were praying to God and you asked your best friend to also please say a prayer for you; except in this case you are asking the saint, rather than your best friend, to please say a prayer for you.
So when I say I “prayed to St. Anthony” to help me find my lost keys, I am actually praying to God/ Jesus to find the lost keys and asking St. Anthony to pray along with me to God/ Jesus. This is permitted for Catholics.
Wearing a saint medal is also permitted for Catholics, as long as you realize it is just a reminder of the saint, or a reminder for you to say a prayer to the saint. It is not a lucky charm or something superstitious. If you don’t happen to wear the medal on a particular day, you can still pray to the saint just the same and get all the same help from the saint.