The word "dojo" is often translated as "school," but that translation fails to capture the depth of the word. Translated literally, "dojo" means something closer to "the place of the way." It is considered to be a sacred place for the transmission of a traditional method of some sort, such as a martial art or tea ceremony. The word comes from "dojo-ji" which was an adjunct facility to a Buddhist temple where learning took place.
Typically a classical dojo will consist of an area known as the "shomen" or "kamiza" where a shinto shrine or other display of significance resides. This is where the head of the dojo sits. The three other sides were known as the "shimoza," at the rear or entrance of the dojo, the "shimoseki" where the lower grade students would sit, and the "joseki" where senior students or VIP visitors would sit. Each of these directions are traditionally associated with an element, a philosophical concept ( honesty, virtue, sagacity, rectitude, intellect), and a direction (North, South, East, West). These were typical categorization schemes associated with Shinto or Tendai Buddhism. No singular layout was "correct." The most common feature was an esteemed place for the shomen away from the entrance, and the seating of the sensei and VIPs away from the draft and noise of the entrance.
Of utmost importance is the respect of the training space. It should be kept clean and tidy. Students should assist in the cleaning of the floor, dusting, and putting away of items. Food should not be brought into the training area, except for particular ceremonies (New Year's celebration, for example). Sometimes tea is served at breaks during training in some dojo, and this is acceptable. The point of the dojo is training, and this should be kept foremost in mind while in the dojo.