The altar, the holy table, should be the most noble, the most beautifully designed and constructed table you can possibly find. It is part of your sacred space. It is holy and sacred as the focal point of your personal worship space, so it should never be used as a table of convenience or as a resting place for papers, books, or food that are not part of a ritual or special spiritual purpose.
Candles, flowers (dried, fresh, etc.), statues, crystals, herbs, and other items are desirable for decorating the altar. Try to associate your altar items according to the seasons and moon phases. It is wise to connect to the Earth, and observing one’s environment is a wonderful way to do so.
Altars may be erected anywhere for any reason. For example, an altar may be arranged on a table inside during the season of spring with flowers, rocks, and feathers native to one’s area. This altar celebrates spring and is a pleasant reminder of the Earth’s beauty and bounty.
Altars can be as complex or simply as you would like.
My altar is arranged on my dressertop, facing east (towards the rising sun). On my altar, you will find candles, Tarot cards, crystals, and other items of direct correspondence to whatever I am honoring or celebrating.