One aspect of gamebooks that increase their interest, I find, is the concept of the 'hidden choice.' In other other words, you complete a section and are confronted with some options, but there is another option available that won't be listed but does exist. Giving a quick example:
"You arrive at a T-Junction. A lit bronze torch hangs on the north wall. Looking down the east and west tunnels they both go on into the distance, although you can see an open door a few metres down the east passage, in the north wall."
If you wish to go down the east tunnel, turn to ~156~
If you wish to go down the west tunnel, turn to ~311~
There is another option here though, hidden from the reader, it is:
If you wish to remove the torch from the north wall, add 30 to the reference number you are reading at the time and turn to this new reference number.
Applying that here, you would add 30 to page ~35~ and turn to page ~65~ instead.
These types of choices are normally worked into the story by finding clues earlier on in the adventure. For example, if you make the correct decisions earlier in the adventure you will come across a scroll that tells you that a secret passage can be opened and closed by removing/replacing a bronze torch from the torch holder at a T-Junction within the network of tunnels. It is at this page where the application of the clue is given in the following way:
"If at any stage during your adventure, you arrive at a T-Junction that contains a bronze torch you may remove it and activate the secret passage by adding 30 to the reference number you are reading at the time and by turning to the new number."
I believe these type of choices are greatly underused in gamebooks generally and could be utilised far more greatly, enhancing the gamebook experience.