A good picture is worth a thousand words. Especially since the buyer can't actually see and feel the quilt.
We will use up to 4 pictures for each quilt.
The best view of a quilt is flat against a wall. We do not use pictures of quilts laying on the floor--it distorts the view too much. Quilts actually on a bed in the manner they would be used are okay as long as the pics are clear and well lit. Please remove all the extra "stuff" that would be visible in the picture. (And no one wants to see a child or a pet laying on a quilt they are considering buying, no matter how adorable they are!)
When we take pictures of wallhangings etc., we carefully pin the quilt to a 4 x 8 sheet of styrofoam insulation board (from the home design center--Lowe's, Home Depot etc.). We then can move it around the house until we find the best light to take pictures or we can take it outside, weather permitting. (Hint: We also use this board, covered with flannel, as a design board for quilting and sewing.)
Be sure to have plenty of light in the room for pictures. Even if you have to flip the drapes up over the drapery rods (during the day) while you take pictures it will be worth the effort. Flash attachments do not give enough light by themselves so turn on room lights if you must take your pictures at night. The best and clearest pics are taken outside with daylight--weather permitting.
Take pictures "straight on", not from the side and focus on a spot in the center of the quilt for the least distortion. If trying to get the details to show up, stitching etc., try lighting from the side.
Search YouTube and Google (Bing, whatever) for free photography lessons and videos on how to get great pictures. Also Craftsy.com has several excellent photography classes.
Use picture editing software to get the best possible picture, a good free one is Irfanview.