If you don't know then you are a novice searcher. That's okay. Be prepared to rack your brain. Try everything you can think of. Throw out what doesn't work and keep what does. When you are correct, Fenn lets you know in the solve itself.
Thanks you for asking and taking me seriously. For that I will give the clues.
Novice Clue: Fenn's verbal and illustrated hints do not all apply to the same solve.
Novice Hint: The Poem Decodes into two additional pages.
Advanced Clue: The Hanging Tree is at 23 and I don't mean the tree in Colorado.
Advanced Hint: The drawing of Fenn walking over the cliff in one of the books has him wearing the beltbuckle. The beltbuckle in that drawing says "Clue" on it if you look close. It's actually two clues.