There is a very easy outline for the Book of Revelation; it is found in Revelation 1:19.  It neatly divides the 22 chapters of the book into three sections.  People who think Revelation is difficult to figure out are wrong!  It is actually one of the easiest books to outline and follow sequentially!

Besides the key verse (1:19), Revelation has a key phrase, "Behold, He cometh" (1:7a).  The Subject-Theme of the book is the Lord Jesus; specifically, His Return in full, unveiled glory, when every eye shall behold Him!  Next to the subject of faith, there is no subject from Genesis to Revelation mentioned more than His Second Coming!  For every one time the First Coming is mentioned, the Second Coming is mentioned 8 times!  Thus, it behooves us to learn all we can about Christ's Return (which will be in two stages: the private Rapture and the public Revelation - His First Coming was also in two stages: private and public).