Depends on the tradition. Lunar worship/magick pre-dates the point in time where sigils became a thing, so the various aspects of the moon are represented with symbols associated with certain deities et al. There really are not any traditional sigils for the moon.
Again, the same thing If you are referring to the God of the Hebrew texts then writing and speaking it’s name should be enough; the old school Hebrews would not even mention the name of YHWH out loud for fear of drawing it’s attention, as YHWH was considered almost demonic by those people. That’s one of the reasons there are so many godnames for it, such as Adonai (master). They are used in place of it’s name to avoid drawing it’s attention.
Well, this is a very good question. And to you Muslims out there, I’m sorry, but it’s time to reveal the truth about you guys actually worshipping the Moon! Also, when you all march around the Kabba (the Black Stone) in Mecca to drink from a Vagina shaped fountain embedded in it (Licking the pussy!).
NO Muslim will admit this although the Freemasons and Shriners have revealed this information in their ceremonies for centuries!
The point is the Moon Goddess sigil is the same as the symbol of Islam. Her name is (by Culture):
Diana or Artemis
Babylon = Semiramis, also known as Sin, Ishtar (Ashtare, Ostare, or Easter)
Egypt = Isis
Greek = Aphrodite
Roman = Venus