Superstitious describes a person who believes in superstitions, or a thing that comes from such a belief. Two patterns: about people — 'my grandmother is very superstitious', 'he's superstitious about numbers' — and about things — 'a superstitious fear of the dark', 'superstitious rituals before a game'. Notice 'superstitious about + noun', which is how you name the particular thing someone worries over. The tone matters. Said of someone else it is mildly critical, though usually affectionate rather than harsh — the kind of thing you say about a relative with a fond smile. Said of yourself it is almost always softened and half-joking: 'I'm not superstitious, but…' is such a common opening that it is nearly a fixed phrase, and it is nearly always followed by proof that the speaker is a little bit superstitious. Athletes are the classic example, wearing the same socks all season because the team once won in them.