- Solutions should be computer or human checked for accuracy (if you ever solved an incorrect puzzle, you know where I come from)
- Multiple possible solutions are generally avoided for any given puzzle
- Games need to be new to me (some combinations migrate from one book to another until everyone can recognize them by heart)
- The quality of the games has to be rather good, preferably - played by grandmasters
- In terms of layout or presentation - solutions are easy to look up, ideally - without the risk of seeing solutions to the next positions (whether the puzzle is available online or in a book)
These are the qualities that expect from books/collections that use to train my own skills, so I try to do my best to ensure that ebooks that I create, or tactics that I post on this blog - follow these guidelines as well.
What else do you expect from a high quality chess puzzle book?
PS. Note, that I am referring here to practical positions, not the skillfully constructed "mate in two" positions where one side has huge amount of extra material and aims to give mate in as few moves as possible. Those can be quite elegant as well, but are generally a different beast altogether.