Unlike the other seven planets, Rahu & Ketu do not have their own zodiac signs. These are mathematical points/nodes intersecting the paths of the Sun and the Moon, causing eclipses on the Earth. Hence, these are treated as 'shadow' planets.
With respect to one's birth chart, one can perceive the favourable or unfavourable position of the Ketu, based on the following "symptoms":
Benefic Effects: Devotee of goddess Chandi, lord Ganesha, lord Shiva, having faith in god; professionally doctors; salvation, chanting religious mantras & songs, eager to have bath at holy river/place, keen to know about different religions; good knowledge about animals; fulfillment of desires, luxurious life style.
Malefic Effects: Fever, miseries, wounds, arguments, eyes & stomach problems, small pox, wasteful consumption, harm to enemies, jadu-tona (black magic); liking towards animals with horns, colourful birds, cunning, impatient, aspiring for salvation.
It is difficult to judge or ascertain in which category a person exists. It is not usual that every benefic or malefic character would be affecting a person at the time. There can be mixed effects too. To reduce the malefic effects, the understated remedies can be considered suitable: