The first thing to consider is where the wardrobe will go. Do you have a special niche for it, or will one need to be created? Will the closet need to be built into the wall, or will you need a free standing wardrobe? Evaluate the space in which you want to build your custom wardrobe, and see how much space you can work with.
Evaluating the space will allow you to know what type of wardrobe you want, whether fitted, built in, walk in, or free standing. Once you have determined the type of wardrobe you desire, you will then need to take the measurements for your wardrobe design. You will need to measure the height, the width, and the depth of the space for your wardrobe, and these will need to be written down on a paper. Make sure to account for the space around the wardrobe, as well as the any incline of the roof.