I don't outline.
For me, the fun of writing is discovering the story as I go. If I outline, I know the story. If I know the story, I don't bother to write it. (Same reasons why I don't read the end of books first: if I know the end, I don't bother to read it.)
BUT. This does not mean I don't need a bit of forethought.
I say I don't outline, but I do have a general idea of where the story is going. I need to know that much, at least, so I can set up the story. Without conflict, I don't have plot--so I need characters who can find that conflict and solve that conflict.
Even for people who don't outline like me, I do find it necessary to list out the main points I want to get to in the story. That way, if I feel as if I'm drifting or rambling, I check those main plot points. Does the rambly bit fit with one of the plot points? If so, I carry on. If not, I delete and start over.
And this is where the only problem with writing without outlines comes in for me. Sometimes, I get stuck. I have characters here and I need them there. And they don't want to go.
How do I build that bridge? I try to think of logical conclusions. Going backwards often helps. What do I need them to do? What, logically, would make them want to do it, or need to do it?
So, how about you? How do you get un-stuck?