Research is touchy. Especially for writers.
Women don’t like to feel made a fool of, or gullible. Men know everything and want to prove it. Readers, in general, don’t like being data dumped upon.
There is a fine line between knowing the topic and making sure everyone knows you know the topic.
You Have to Know the Topic
As a writer though, we have to know the topic. At least so far as the character has to know the topic. We have to know city layouts, building designs, medical practices, allergic reactions, accents, clothing trends, how cell phones work and every possible way a wizard can use his spells.

There is a balance though. Readers don’t want know-it-alls, they know things too, much to a writer’s surprise. Here is another surprise: over 80% of male readers will put the book down for good if something they know to be true is wrong in the book.
Have a character that’s a mechanic and working on a Ford engine? You better know the timing sequence and the difference between a 351 Cleveland and a 351 Windsor. If you get it wrong, that male reader will never believe another thing you say, he will put the book away, disgusted and if your name is on the cover, he won’t ever pick it up.
Over 80% of male readers will put the book down for good if something they know to be true is wrong in the book.
Female readers are a little more forgiving. However, if you get something wrong and they believe you (say they don’t know about all-roller engines) and then later they bring up their new-found knowledge thanks to you, they will feel belittled and ashamed and guess where the blame goes? You’re right. And your books remain on the store shelves.
Prevention is Key
The good news, however, is that this is easy to prevent. Just do your research. Just like in school, you need to head to the library or the digital version. While you don’t need to cite your sources in a bibliography, you still need to exercise the same cautions.
Stay away from wiki sites, where anyone can contribute. It may be true, but how will you know if it’s not? Willing to risk your book sales and possible next book publishing a wiki is right? I didn’t think so.
Stick to fact sites, and stay away from opinions (unless of course there is going to be an argument between two mechanics in your story.. one should be wrong).
I Prefer Personal Investigation
Personal investigation is the best method. Writing about how a policeman does an investigation? Go to your local P.D. and ask one. Ask doctors medical questions or procedures. Don’t rely on reruns of ER. Ask engaging questions and only accept essay answers. “Yes” and “no” aren’t going to cut it. Don’t ask yes or no questions.
Join forums and ask members for help. Specifically, if you know nothing about the topic. As an example, I am writing a gore-horror book that deals with some self-mutilation.
I have joined a forum on a specific topic that is covered to ensure I have the effects right. I ask things like “How much bleeding?” or “How long until you can walk?” and “How long does the pain last?” and even “Would you do it again if you had too?”
Ask and learn everything you can. You won’t use it all, but knowing it will make your writing better.
Always do Research, No Matter the Project or Scope
Research is key, and even if you are writing complete fantasy, there have to be some elements of truth that the readers can cling too. Physics, for example. Your planet may not have gravity, but a reader may not know how to deal with this. You need to know enough about gravity so you can effectively remove it. It has to be reasonable. It has to be believable.

Do NOT bull shit your readers. They will know, they will find out and YOU will be the only one that suffers because of it.
So, do your homework, do your research. No matter how tiresome or tedious it is, it needs to be done. Your writing, your project and possibly even your sales will thank you for it.
A Final Reminder
Just one thing: when you learn everything about the topic, keep the knowledge to yourself. Don’t data dump everything you learned into your pages. Let enough leak out that people will know you know what you’re talking about. Less is more.