Altars are used by most practitioners of Luciferian Witchcraft, as well as those of other Witchcraft traditions. They are a valuable tool to help you develop the focus of your mind and will.
While some will tell you that there are hard and fast rules to setting up an altar such as "the candles must be placed in exactly these positions" or "the athame must always be here", the truth is that none of it is true. In fact, not all practitioners setup or use an altar at all.
The whole of the Art of the Wise - the practice of magick - is in learning to become in tune with the universe around you, and to become able to focus your mind and will with such clarity and power that you literally make your will into being. Whatever will help you to gain this focus is what you need - and it is a very individual thing. An altar generally tends to be a useful tool.
I have an account on DeviantArt.com (http://enlightenedoflucifer.deviantart.com) where I have setup a number of example altars for various purposes - but they are just that - examples which are meant to inspire you to find what works for you.
Altars can be setup for your general, everyday practice, or you can create a dedicated altar for special occasions, sabbats, or purposes. You can even have more than one if you want.
The rule is that there are no rules. Whatever helps you develop your focus and find success in your practice is right for you.
It is hoped that you find inspiration here.
So mote it be.
High Priest and Magus
The Liberated Of Lucifer