Your selection will depend on the color of the room, privacy required, how hot or cold you want it to be and the amount of light you prefer entering your room. For instance, if you want to optimize the amount of light entering your room, choose a light fabric with light color and soft patterns on it rather than a heavy drape. If your window gets a lot of sunlight, avoid using dark colored materials, as they will fade quickly. Other parameters you should keep in mind while choosing fabric for curtains is size of the room, the shape of the window and the color and upholstery of the furniture.
If your are buying curtains for a room that is used formally, use fabrics such as brocade, damask, faille, silk, velvet or velveteen. If it is for an informal room choose from bouclé, chintz, cotton sateen, linen and sheeting. If it is for a casual room choose from broadcloth, burlap, canvas, corduroy, denim, muslin, poplin, suede cloth or tweed.
Don't forget to check the label for washing instructions.
Before you look for fabric make sure you measure your window accurately. To determine the length of the pole to hang the curtain from, you first have to decide on the length of the curtain: sill length, below sill length or floor length. The thickness of the pole will also depend on the weight of the fabric. The width of the curtain should be a little more than the width of the window. It can be up to three times the width of the window if you want a lot of gathers.
Lining your curtain protects it from damage due to dust, sunlight (especially if its dark colored curtain) and in insulating the room. You need not line your fabric curtain if they're light, you don't want to cut off too much sunlight and the room temperature is controlled.
