Supposedly every human takes about 35,000 decision every day, most of them unconsciously or by gut feeling. But for those decisions where we still have to think deeply, there is a lot that can go wrong as Daniel Kahnemann wrote in his iconic book “Thinking, fast and slow”.
MIT press has recently published an eBook describing the basics and processes involved in taking decisions in a structured way - a great resource! Disclaimer: it’s a technical textbook about algorithms in the area of decision theory. So it’s more relevant to AI enthusiasts and people building smart agent systems, than for the average person desiring to buy a new car.
The book is licensed under Creative Commons and can be downloaded without registration or subscription directly as PDF. Happy hacking!