Thoroughly

From Dungeons & Dragons module B2, Keep on the Borderlands:

The use of this module requires a working familiarity with its layout and design. Therefore, the first step is to completely read through the module, referring to the maps provided to learn the locations of the various features. A second (and third!) reading will be helpful in learning the nature of the monsters, their methods of attack and defense, and the treasures provided.

From module B3, Palace of the Silver Princess:

Before beginning the adventure, the DM should read this module thoroughly to become familiar with its details.  

From module B4, The Lost City:

Before beginning the adventure, please read the module thoroughly to become familiar with the Lost City. 

From Advanced Dungeons & Dragons module A1, Slave Pits of the Undercity:

Before commencing play, it is recommended that the DM read the module thoroughly and become familiar with the information given. 

From module A2, Secret of the Slavers Stockade:

Before beginning play, the DM must read all parts of the module thoroughly. 

From module C1, The Hidden Shrine of Tamoachan:

It is recommended that the DM read the module thoroughly several times before play starts, making notes in the margins where useful.

From module C2, The Ghost Tower of Inverness:

It is necessary that the DM read the module thoroughly before play. It may be useful to make notes in the margins at some points. 

From module S1, Tomb of Horrors:

Please read and review all of the material herein, and become thoroughly familiar with it before beginning the module. 

From module S2, White Plume Mountain:

Please read the entire module through and thoroughly familiarize yourself with complex areas before beginning play. 

From module S3, Expedition to the Barrier Peaks:

Be certain that you are quite familiar with the entire module, and read each encounter section carefully.  

 etc. etc.