First of all, we need to know what a genre (jon-rah) even is. A genre is an area of interest. The Thriller/Suspense category is one type of genre. There is Romance, Action/Adventure and Horror just to name a few. There are a lot of different kinds of genres.
A race against the clock, like in the Andromeda Strain, or even in something as simple as Cinderella, is thrilling. It is thrilling to read about a daring escape, where some of the characters get out, and some of them don't. Some of the characters may even die in the process. And a baffling incident is something that is so bizarre and intriguing that you must read it to find out what happens. It is suspenseful and thrilling.
The Romance genre is pretty self-explanatory, but there are different kinds of romance. There are Glitz, Regency Romance (set in London or Rome for example), Bodice Ripper (lusty and steamy), and Historical Romances. Romances can be mysterious and suspenseful with a female protagonist, or science fiction like in "Somewhere in Time."
The Action/Adventure genre can include rescue stories, continuous pursuits, secret missions, mythical quests, daring escapes, and military campaigns. Yes, daring escapes can be both thrilling and adventurous. Try to think of some movies that might fit into one of these categories.
Horror stories include anything about ghouls, ghosts, monsters, psychopaths, the occult, psychics, magic, nature in chaos, superstitions or legends.
Okay. Now that we know a little more about some of the different kinds of genres, let's talk about how to analyze them.
The best way to begin is to go to a few garage sales or thrift stores and buy a bunch of old books that you won't be afraid to mark up with highlighters, pens and notes. It is actually quite fun and I do this to all my books. The first thing you need to decipher in these books are the moral views. For example, in almost all Westerns the character dies with his boots on, and it is a known fact that you never shoot anyone in the back. In a Regency Romance love always wins. These are the kind of things you will be looking for. Go ahead and analyze some books and see what you come up with.
Next, determine the time frame that each genre takes place in. A Thriller can be accomplished in one day, like in a "wait until dark" story. An Action/Adventure can take several weeks to accomplish. A good mystery seems to run about three days and nights.
Try to gauge the time frame and pace of the story, like if a subplot shows up by chapter three and in chapter twelve the two plots join. Count the number of chapters to get an approximation on each type of genre. Count how many pages are in each chapter. This really works to learn how each genre is paced.
Note the settings. They must ring true. Westerns can only take place on trails or in cattle towns for example. Most spy novels take place in major capital cities. Be conscious of the taboo areas as well. Christian novels will not contain foul language or sex. Neither does a Regency Romance contain sex. But Bodice Rippers are full of it.
Finally, become a master of the language. Learn about different eras and the way they talked. Language evolves and changes with time. New words are invented almost daily. The dialogue must sound natural and comfortable for the time period. After all, would a cowboy in the old west say, "Later, Dude?"
Take notes on each type of book you study. Learn the genres. Especially study the kind of genre you are interested in writing. Study them, decipher them, analyze them. Then, when you write your own horror story, it will follow the basic pattern of all the other successful horror stories.
Good luck, keep learning, and keep writing.