My current story is purposely in a set up that I can make it up as I go, to a point. I have very specific key scenes and scenarios that I have to hit, but I already understand the order they need to be in. So everything else can be put in between. I have a small layout of the order that important stuff needs to happen, then I brain storm and come up with the events that lead up to it.
My comic is very character development heavy, so as long as the characters are developing at a stable pace, and reach a certain style of emotional state (it's a romance, so you get the idea), then I have done it right. Mostly.
I do write out scripts for dialogue, settings, all that as I come to the next chapter. But I write chapter to chapter, rather than having a giant story already sprawled out. I'd feel too confined if I worked that way, and I'm still learning, so this way allows me to improve. I think.