Don’t reveal everything, and maintain an air of mystery around yourself, your personality, and your life. You should also make sure that you do not resort to dropping hints - this way, people could end up figuring out a lot of stuff about you.
Don't always be reachable; let people learn to get in contact with you the hard way. When the phone rings and you see a recognisable number, don’t answer and the let phone ring. Similarly, if your door bell rings, you can either not open the door at all, or ask someone else to get it.
When people ask you to join them for some event, never commit unless it is absolutely necessary to do so. Later, you can choose to either turn up to the event, or avoid it.
When in conversation with someone, do not reveal your interests, or the things you like to talk about. The idea is to keep others wondering who you really are, and if they know your likes and dislikes then you aren’t too much of a mystery to them anymore. If they insist that you give them a straight answer, respond with vague replies like your favourite things keep changing according to your moods.
Refuse to commit to participating in school/community projects. However, in order to keep cordial relationships with the community members, offer occasional help when people don’t expect you to show up. You cannot be known as a serial killer, rapist, or some other creep who keeps to himself and doesn’t want the community members to bother him, as this will isolate you and could push you into leaving town if your neighbours lodge a complaint against you. If you show up to events every now and then, people will see you as friendly but elusive and eccentric, as opposed to threatening.