(((I decided to just make a journal entry about this one, since there's really no drawing required here))))

The way I see it, if you're reading this, either you have a story you're working on or you're desperately trying to come up with one. Maybe it isn't coming together quite like you pictured it? Maybe there's too much to work with, or you have too many options to choose from? Maybe you're like many people and can't seem to come up with a good satisfying story no matter how hard you try!
Chances are, YOU ARE THINKING TOO HARD. Sure everyone wants to be the person who writes things like 'Inception' that are super complex and insightful and fun to watch/read/enjoy, but the point is that, when you boil a plotline down to it's basic elements, you should be able to summarize it in ten words or less.

Inception: Man is hired to deceive someone.

Think about it. Watch the movie again if you have to. The MAIN PLOTLINE of Inception is Leonardo DiCaprio's quest to make a guy think something that's not true at the behest of an Asian businessman. What about all that dream nonsense? WHAT ABOUT ADORABLE LITTLE JOSEPH GORDON-LEVITT??? Both of those things, though very important, are secondary to the main driving plot of the movie.

If you cannot take your giant space opera down to it's basics—a noun, a verb, and a direct object—you have a problem. The problem is you don't understand what your story is basically about. It has become so complex that you can't tell what's most important anymore: what's really driving the story.

But, at this point, if boiling it all down to ten words or less is a little too difficult, let's take a step back. Summarize your story in one grammatically correct sentence (aka, not a run-on sentence, that's cheating.)

Inception: At their employer's behest, a man and his team of specialists must infiltrate a budding business tycoon's dreams to stop his company's rise to power.

Now THAT sounds a little more like Inception. We have the dream element, we have a nod to adorable little Joseph Gordon-Levitt, but at this point we don't have names or other extraneous information. Names and subplots are tertiary in the summary hierarchy. In the noun-verb-object summary, we established the WHAT. WHAT is this story about. In the single-sentence summary, we established HOW (infiltrate dreams) and WHY (stop rise to power.) ALL OF THESE, ON A BASIC LEVEL, ARE MORE IMPORTANT THAT THE WHO, WHERE AND WHEN OF A STORY.

Too often people get caught up with a single character, wanting to write an entire epic around this singular figure, only to realize later on that their story is severely lacking in structure and reason. Too often people get caught up in a single place, wanting to build a world or universe, and the same thing happens. Too often people pick a point in history they really like but can't seem to create a story around it. Unless you plan to be the only person who enjoys your stories, you'll have to take a step back and think critically about your storytelling.

So, to recap, in order of importance:

WHAT (happens)

WHY (does it happen)

HOW (does it happen)

WHO (are the characters)

WHERE (does it happen)

WHEN (does it happen)

Fit your storyline into these parameters, and be as vague as possible. Continue to break it down further and further until you've reached the point where you can't simplify your sentence any further. Only then will you realize what is truly the most important thing in your story. Once you find THE MOST IMPORTANT THING, then you can begin building back outwards, adding information bit by bit, editing out the subplots and extraneous information that are cluttering your story. Use the noun-verb-object sentence as your center, and try not to lose it again.
Hope this was helpful and not just me banging on my keyboard for an hour. Next I'd like to post about creating actual plotlines! THE ACTUAL FUN STUFF!