A quick tip from current personal experience:
When you're developing a story, and find yourself getting stuck in the meanderings of the plot, it pays to look back at the original way you presented the story's idea - no matter how concise.
You'll often discover that your development has strayed a lot from the original kernel of inspiration - even when you think you're still staying true to it. Especially when you discover you've become unclear on whose story it is, or what exactly the main throughline is supposed to be among the several plot strands you are developing, the answer - or at least your initial answer - will be there right in front of you.
The personal experience I mentioned: I'm developing an idea for an episode of De Kampioenen, but I've been stuck for days on end. I'm trying to make it a farce with mistaken identities and such, but though I have several ideas for funny scenes, the two main plot strands grew too far apart, and one of them just got bigger and bigger and bigger without any end in sight or any logical climax presenting itself.
So when I looked at my original version of the idea again today, I discovered that I actually kept the mistaken identity element to a minimum, and instead of having several characters pretend to be the other without anyone knowing, I originally had them all in on that piece of the action. Which, thinking about it, made a lot of things fall into place and, more importantly still, immediately gave me ideas to curtail the over-extended plotline.
It's too soon to tell whether this'll allow me to end up with a satisfactory, useful story, but it definitely pointed me back in the right direction. So try it - this little tip might help you too.