what do you need to see / read before deciding to buy a book?

• Is the book written in a language I can read?
• Who are the authors? Have they done something that I dream of doing?
• Did someone recommend it to me? (much easier to buy - either by a friend or an author from another book or an authority on the subject)
• Is it available on Kindle and Amazon?
• Is it something that is going to help me with my current goals (like this month) or is it something for the future (I'll bookmark)