I have a bachelors degree in a non-science related field so I have never conducted a research study myself. I find it very difficult to understand if the study I am reading is well thought out, with good practices or just comes from shady interests or publications.

How can I be better informed to distinguish between good and valid studies from the others?

How do I know if a study has been peer reviewed and what were the conclusions of those reviews?

How do I know if the methodology chosen for trials was right or flawed?

Is there any "Research Studies for Dummies" resource out there I can read to improve my knowledge on this?

Thank you