You must pray every day, asking God to reveal his plan for you.  Do not ask yourself, "What do I want to do with my life?"  Rather, you should be asking:  "Jesus, what do you want me to do?"  Listen for the answer.  Listen with your heart, not just your head.  The Church must also be involved in the discernment process.  Listen to what other people see in you.  Your bishop is the one who will ultimately decide who is and who is not called to be a diocesan priest in his diocese.  He is assisted by the vocations office and the seminary staff.