How I Prepare An Adventure Under Ideal Circumstances
This is a riff on a workshop I attended while in high school in 1983 called, "How To Read A Textbook."
Evening One
1) Skim quickly through the entire adventure. Read all the headings and look at all the illustrations, taking time to look over the maps. Allow myself to stop anywhere that grabs my attention, but don't read more than a few sentences.
2) Go through the entire adventure reading the first sentence of every paragraph AND all the words that are in bold. Allow myself to stop anywhere that grabs my attention, but don't read more than a few sentences.
3) Check the forums for any GM discussions about the adventure.
Evening Two
4) Read all of the adventure. If I have printed out the PDF, I do the following during the main read-through: a) Underline the most important sentence of each paragraph. b) Highlight all the Skill checks with green. c) Highlight what the PCs need to know after the encounter or conversation with yellow. d) Write down on a legal pad any spells or combat rules I don't know or can't remember.
Evening Three
5) Skim through the adventure. Make index cards for all the major NPCs. Make a couple of notes about their appearance and location. Write down three things they might say during a psychotherapy session with their analyst. Work the backstory into a couple of the sentences. (With Burnt Offerings, I did this with a database because of the large number of NPCs. Instead of writing three things, I copied and pasted pertinent information about each NPC as I came across it from the PDF into the database.)
Evening Four
6) Pre-draw any complicated maps (like the Sandpoint Glassworks) on the large presentation board size graph paper with 1" squares that is available at most office supply stores.
7) Make index cards for the combat encounters. I still use the free ones The Game Mechanics made for D&D 3.5 if I have access to a printer and card stock.
--OR--
6) Prepare maps and tokens for VTT software.
Evening or Morning Before The Game
8) Skim the adventure and the NPC cards, reading what I have underlined and highlighted.
9) Review the spells and rules I listed on the legal pad at a website like d20pfsrd.org. Make brief notes on the pad as needed.