Window facing direction is the first thing you have to consider to when buying ready-made curtain. Take south direction for example, light shortage is the main problem of south direction where semi blackout curtain or some translucent curtains are best used here with thinner material is all right, the same to quality to bedroom. But north direction, curtain hanging up on front north window should be a thick and heavy curtain in warm color to increase inside room temperature to keep room warm.