"And I will give you shepherds after my own heart, who will feed you with knowledge and understanding." (Jeremiah 3:15)
There are four steps that any man must take when praying about becoming a priest. The first of these is to decide whether to become a diocesan or religious priest. A diocesan priest is bound to his bishop through his ordination to the priesthood. A religious priest is bound to his religious congregation and his superior through his ordination. A diocesan priest is the parish priest you see every weekend. A religious priest's focus depends on the religious order or congregation he belongs to.
After discerning diocesan or religious priesthood, the next step is to contact the vocations director for your diocese or for the particular religious order in which you are interested in being apart of.
The third step would be to obtain an undergraduate degree in philosophy, and the fourth step, to enter into a school of theology. Both of these steps are guided by the bishop or by the superior of the religious order in which you enter. Talk to your parish priest or a person you trust if you are thinking or praying about becoming a priest. You can also check out the
Office for Priestly Vocations