Really though, you have to find what works for you personally. Take any idea - let's say you decide that you want to know if eating less red meat is good for you. You can read a hundred studies that have conflicting results. Or you can try eating less or none of it yourself and see how you feel. You feel great? Awesome. Now you know! You don't feel any different? Again, that's awesome. Now you know you need to eat a little more red meat.
One example for me was pull-ups (the exercise). I always assumed you had to do them overhand with a medium-wide grip. They never "clicked" with me and I could never feel good doing them. After 10+ years of doing them the same way, I finally saw a video where a guy explained how different people might need to use different grip styles to feel it best. I tried several of the different grips and found what works for me. No study or book would be able to tell me which grip style I should use. It was just something I had to learn for myself.
For something more science-based, check out examine.com[1]. Anytime I read about a supplement or chemical that's supposed to be amazing, I go read examine.com and find out what the studies say.