Where do you get the information for your research? You find sources. You can read books, talk to people, find articles, etc. There are two main types, primary and secondary.
A primary source is closest to direct subject knowledge. For example, historical documents such as letters, official reports, or field notebooks could tell you what kind of activities your Victorian Egyptologist character would have been engaged in. If your character is a police detective, you could talk to one about interviewing techniques, like I did for Rose’s Hostage.
Or, let’s say you’re writing a story about Neanderthals. Our ancient relatives were experts in the art of flint knapping, so to authenticate your story, you want to learn more about how they made spear points, axes, etc. Since there aren’t any Neanderthals around anymore, if you wanted to actually try your hand at it, you would have to find someone who practices the craft. Quite a few people do it, and you can even take classes. I’ve done it, in archaeology class–it’s fun.
The reminisces of commenters on the London photos page I mentioned are primary sources. Not all primary sources are reliable; even memories can fade with time or become altered. Judges and cops know that eyewitness testimony is notoriously unreliable, but it’s the closest thing we have to actually being there.
You could also read a book about knapping. (I have one!) Or you could read websites and articles about the people who practice primitive tool making. These last would be secondary sources.
Just one or two anecdotes or an article reporting them aren’t enough, unless you’re already speculating. For Tunerville, I found an article about something NASA is researching, and I extrapolated off that. This flying by the seat of my pants wouldn’t have worked with Rose’s Hostage; for the police interview scenes, I consulted with a retired police officer.
Whatever you use, check it against several other sources. You will undoubtedly have readers who know something of your subject, and they will tell you if you’re wrong.