The concept of the sacred space is fascinating for Zoroastrians, as we consider all of existence sacred in its own way and always have. The elements and the cosmos in which they reside as absolutely sacred to us as co-custodians of existence. However, as to formal worship, this has definitely changed throughout time. No one is quite sure what Zoroaster and his immediate followers did in this regard, but from about 900 BCE to 200 BCE, the primary form of worship attested to was directed either to one’s hearthfire or to mounds and peaks where the fire rituals could be done under the beautiful sky. In Parthian times, there were both Ayazans (shrines dedicated to specific divinities) and Atroshans (proto-fire temples), but with the arrival of the Sassanids and their severe iconoclasm, all of these buildings became fire temples surrounding a central sacred fire and it has been that way ever since. However, even those were mostly open (not many walls and doors) and now they are completely enclosed structures.
When you enter a fire temple, you offer bone-dry sandalwood to the fire (this sometimes differs from community to community) and in return, the priests tending the fire give you some of the sacred ash, which you then mark your face with and take some home with you. The fire temples are not places for preaching, but rather mostly veneration of the sacred fire, the conducting of personal prayers, and where the grand Yasna ritual takes place. If it is a temple where the Yasna service happens, then it’ll also have on the grounds somewhere a stream or a source of natural water since it is a part of the formal Yasna ritual. A bell is also usually rung there to indicate the start of each Gah, the prayers done five times a day traditionally, a practice which was later adapted by Islam. Almost all personal rituals and prayers are done either sitting or standing and palms facing upwards, usually also in a way that will not disturb others in prayer.
The writer prefers a mix of Achaemenid and Parthian practices aforementioned, in that the hearth-fire or any fire that is lit for ritual purposes is sacred (and temporary), but fires burning at both shrines and fire temples (of both of the enclosed and outdoor variety) should be highly encouraged. It is important for any religion to have a place for the local community to gather and pray together, speak together, and experience the mysteries of the Divine together. This writer is also not an iconoclast, so elaborate shrines and temples are a definite plus. The Yazata should be paid worship and veneration, as their very title implies (”worthy of worship”) and both the traditional and local cultural Yazata should be represented. For the most part, most people do their rituals and prayers either in the presence of sunlight or any sort of fire (generally, facing any sort of light, which can include computer screens in this day and age) and wherever it is they find themselves when it comes time for their prayers.
Let it be also noted that in most households one will usually find a house altar dedicated to the faith, the contents of which differs per season but will usually always have an image of the Prophet Zoroaster, a mirror, and various implements to represent the Amesha Spenta (the direct manifestations of Ahura Mazda).