From the recruitment practice of intelligence agencies around the world, what are the main aspects to start with?

Faith, loyalty, knowledge and accomplishment, psychological quality and discipline. According to the recruitment practice of intelligence agencies all over the world, the recruitment of intelligence organizations in various countries is mainly based on faith, loyalty, knowledge accomplishment, psychological quality and discipline. The recruitment of CIA must be very confidential. They will put eyes in all walks of life to find people they need, such as technicians who are proficient in a certain skill, people who are particularly influential in a certain field, or people who are naturally ignored and have no sense of existence. These people are best suited to be intelligence agents. After passing the exam, gather talented people together and then select them. Finally, after a series of various exams and tests, see if they can join. Their recruitment is also mysterious, and his background has to go through very strict examination. When recruiting, they won't disclose their departments. They will have a general understanding of the recruits, know their personalities and have enough knowledge of their majors.