For Coordinate geometry it is important that you by heart the basic properties of objects like Pair of Straight lines,Circles,Family of Circles,Parabola,Ellipse,Hyperbola like eccentricity,distance between straight lines etc.
Those who try to derive the formulas in the examination hall are at huge loss and their scores will be affected terribly.
Perfection in these topics will improve your score drastically and these topics are important because the questions asked are easy and you can save a lot of time
--
Ramesh