1) Closet lighting - you have to be able to see what is inside your closet but you don't want the sun shining directly on it either as it will fade things if left open. You can buy cheap lights that stick on anything now and you might put one of them in your closets if they are too dark.
2) The hallmark of a great closet is one that effectively uses all space. You can have bins for storing smaller items or things that you only wear at certain times. Shelves in closets are something that most people don't think of and can be part of a good closet design.
3) Part of effectively using all the space is to do it in a manner that is practicle. You want to make sure that everything in the colset is accessable and visible so that you know it is there. Using all the space does not mean just cramming things in.
4) Use the floor of your closets for bins and shoes and storing all smaller items. Also, the floor has to be orderly so that you can walk in the closet or at least walk in enough to be able to get things.
5) On of the important closet ideas is to make sure that there is airflow and that your closet does not get mold or mildew. If you have an airflow problem, you can wrap up some chalk and put it in your closet to help keep things dry and prevent closet mildew from forming.
6) Use a wood for your closets that do not have a pungent smell. If you use the wrong wood (cedar can be smelly), your closet may make the room it is in smell bad and your clothes may take on some of the odor as well. These closet design ideas are tips you should think about when building or organizing your closets.