People need private tutors for a variety of reasons. In some cases a person may need to master a particular subject in a short period of time; in other cases, it could be that the individual is struggling in a certain area and needs more support than standard schooling may be able to provide. In both situations, a private tutor is a common solution to provide focused assistance to help the individual who needs instruction in a particular subject. A wide range of tutors exist, but generally they have a few traits in common.
Beyond anything, private tutors need to know what they are talking about, and ideally have some type of certification or proof of their knowledge. This means that they should really be considered experts in their field, or at least proficient in the subject. If they are tutoring junior high school students in math, for example, then they should have a strong ability in high school math, at the very least. If not, they would have difficulty finding work in private, home tutoring.
Tutors are also usually not certified as teachers. Those who have teacher certification tend to find work as teachers, working in classrooms with large numbers of students. Typically, tutors are university students who do tutoring work as a way to earn income. They may be planning on becoming a teacher after university, and tutoring is an easy way to get teaching experience. Or, they may be tutoring others in their chosen field, as a way to strengthen their knowledge of that particular subject, or to use their background to earn money.
Aside from background requirements, those who offer private tutoring need to be able to work well in a one-on-one situation with people. A private tutor implies that there will only be one person being taught, so it is important that the tutor be comfortable working with someone else, and possess the ability to motivate and properly adjust their tutoring techniques to meet the needs of the person they are being paid to help.
Tutoring is not for everyone and private tutors tend to be somewhat similar in their experience levels and interests. As stated, most tutors will be university students who have enough knowledge of a particular subject to effectively teach someone in a class beneath their level. They are also people who work well in one-on-one situations and have some ability to teach others. Ideally, they will be people who have a passion to help others learn, and if they want to be successful, they will be able to produce positive results.