Greetings,
I contend that we tend to get the interpretation of the Revelation
ass-backward (if I may put it this way). The rule is that more clear passages on the same subject interpret the less clear. But often, I have seen the exact opposite rule followed into nonsense.
Regarding helpful reference works, I suggest Isaiah, Danial, Ezekiel, Numbers, the Pentateuch, plus the rest of the 65 Books that came before.
IX. The infallible rule of interpretation of scripture is the scripture itself; and therefore, when there is a question about the true and full sense of any Scripture, (which is not manifold, but one,) it must be searched and known by other places that speak more clearly.y
y 2 Pet. 1:20. Knowing this first, that no prophecy of the scripture is of any private interpretation. Ver. 21. For the prophecy came not in old time by the will of man: but holy men of God spake as they were moved by the Holy Ghost. Acts 15:15. And to this agree the words of the prophets, as it is written, Ver. 16. After this I will return, and will build again the tabernacle of David which is fallen down, and I will build again the ruins thereof, and I will set it up.
Westminster Assembly, The Westminster Confession of Faith: Edinburgh Edition (Philadelphia: William S. Young, 1851), 20.