You know how they always used to say writers should write about something they know? Well, that's silly. What writers should write about is something they feel.
Think about your favorite stories. They can be books or movies or TV series or songs, just as long as they have a narrative. Concentrate on the ones you love the most, the movies you watch over and over or the book you reread every summer or the TV series that ran three years longer than it should have but you watch it in reruns anyway.
Then melt those favorites down to their bare essence. What we're looking for is the themes you are most responsive to.
Take me, for example. I love Consequences. I realized that when I was in high school and saw The Desperate Hours on TV and immediately wondered what happened to the family as a result of all they'd gone through. I also love Families, which is why I'll see any version of Long Day's Journey Into Night that shows up. (and how I wish that Paul Newman and Joanne Woodward had once played James and Mary Tyrone). I also love How Things Get Started, which is why I prefer the early parts of biographies to the middles and ends.
Put Consequences and Family and How Things Get Started together, and you end up with a lot of my YA fiction, including Life As We Knew It and the dead & the gone.
But this isn't about my favorites. It's about yours. Say you love The Wizard Of Oz. Well, that's about Quest and Friendship. Jane Eyre is Love And Acceptance. Or Gone With The Wind, which I never read but I did see the movie. That's about What You Can't Have (at least that's what the movie was about). Macbeth is about What You Can't Have also, although I like it for the witches and the murder.
Everyone has certain themes that resonate strongly within them. The writing that's the most fun (and there's not much point writing unless it's fun) is the writing that allows you to explore those themes.
Let's look at What You Can't Have. Scarlett wants Ashley, and one traditional version of WYCH is a romantic triangle. You want your best friend's boyfriend, for example. But Romeo And Juliet is also WYCH (I guess Shakespeare liked that theme, understandably since it has conflict built in). An Armenian girl in love with a Turkish boy would work. So would Scarlett in love with Ashley only Ashley's in love with Rhett. Or maybe you're a nice American girl and you've fallen in love with Gorgo from the Planet Zantac and the problem is Gorgo is a plant, like a dandelion puff, and he's programed in three months time to be blown into a thousand different spores which will sprout into a thousand new Gorgos.
It's very frustrating to have a meaningful love affair with a plant.
But the great thing about WYCH (about all themes) is that it doesn't have to be limited to love (Macbeth proves that). It can be about a kid whose father left the family when the kid was young, and what he wants and needs more than anything is a relationship with his father. It can be about a girl with rheumatoid arthritis who yearns to be a cheerleader. It can be about a girl who lives in a community that doesn't approve of education for females and yet she wants to go to college. It can be about a boy with no talent whatsoever who wants to star in the class play. Or a kid who wants a kitten but his sister is allergic. Or an unpopular kid who wants to be class president (which is what Election is about).
The point (other than it's so much fun to come up with these things) is to ponder what your themes are, because now you know you have them. Then once you come up with the themes that have the most meaning for you, start asking yourself what interests you (kittens, plays, fathers, religion, romance, sci fi) and what kind of story best utilizes the themes you really love. And keep in mind, while you're doing this, that it's a very short trip from Tara to the Planet Zantac.