One thing I think is important is learning the traditional aspects of Christianity. Yes, it's a great idea to memorize the 10 Commandments, the Beatitudes, and to read and study the canonical Scriptures. One should study the Sacraments as they're presented in the Catechism of the Catholic Church.
One should also expand beyond this. Studying the more mainstream versions of things helps to give an eye to what those mainstream versions are generally missing in their approach.
While the Mass and the Sacraments in general operate regardless of the individual celebrating them (that is, the Sacraments operate due to the Power of God and not the Power of the Priest), there is no doubt that the particular state of grace of an individual priest, along with the priest's awareness of what exactly he's doing and the intention he's putting forth, have an effect on the Mass and the Sacraments and the people receiving them.
Thus it is our duty as members of the clergy and aspiring members of the clergy to prepare ourselves and make ourselves worthy to celebrate the mysteries. Our integrity and individual spiritual practices matter.
I'll leave you to think of these things.