I keep an altar. There is no "rule" or "tradition". Do what you sense Satan is asking of you. Best suggestion: create something that bespeaks the Satanic to you.

My set up: a simple altar inside an armoire (so that it can be closed for when I have guests.....secrecy and privacy are important). A simple black cloth, a baphomet, two black candles, my Satanic tarot deck (in a wooden box). In the drawer underneath, I keep altar implements that I bring out when I do ritual (chalice, sacred phallus - a hand-held glass phallus that can be easily sanitized and reused, my wand, my athame (used for pointing in rituals, not for cutting or stabbing), incense and censor. That's my set up.

I know several Satanists who have the luxury of having a dedicated secret room in their home where the door is always locked. I think that is a best practice.

Do what works for you. If someone says: "you must do it this way only", listen to what they say, take what works and leave the rest.