My 1969 Mustang Mach 1 has been sitting in a garage for 20 years with all liquids drained. Where do I begin?

My dad just gave me his 1969 Mach 1, and has told me that he drained it knowing that it would sit for a while. Well it's been 20 years, and now that I able to start fixing it, I'm not sure where I should start. I want this up and running as soon as possible. I hope to use this as my project car and begin restoring it. Are there books that would help with this?