For persons preparing for servant-leadership in the church, most denominations have a candidacy process that requires contact with the denomination prior to the beginning of seminary. Since the process varies, all persons applying to a seminary should clarify the denomination’s candidacy expectations prior to beginning theological studies.
Consistent with your denominational polity, contact your local synod (Lutheran), diocese (Episcopalian), conference (Methodist), etc.
Speaking with your pastor is a good place to start in determining what processes your denomination requires for you to become a seminarian. Also, inquire from your local judicatory (diocese, presbytery, etc.) to determine your denomination’s processes for becoming a seminarian.