My method of adventure design usually bears little resemblance to the running of a pre-published game like Carrion Crown. Not only do I like to incorporate a pseudo-sandboxish approach where the PCs aren't led by the nose from one encounter to the other, but where they feel like they have some elbow room to wander. This doesn't mean converting adventures into hex-crawls, but it does mean offering a slightly different approach in terms of addressing the adventure.
Usually, I have several "hooks" and the PCs could potentially follow one of several hooks. Each hook, in turn, has a number of "suggested" or likely outcomes, usually spelled out as vaguely defined scenes or encounters. These aren't exact or precise, because depending on which hooks the PCs prefer to follow, and how they resolve the scenes and encounters, the following ones could be very different either in terms of what they actually are, or in terms of what characteristics they have when the PCs get there; i.e., the PCs might have a more or less hostile situation on their hands depending on what they've done previously.
There is a method that works very much like this already, although it's a bit more organized than my more intuitive approach, called the 5x5 model. Strictly speaking, the 5x5 model is meant to be used to develop campaigns rather than adventures, but it's also been adapted into the adventure design approach. Given that I'm actually attempting to adapt the entire Carrion Crown adventure path into a simplified campaign, I can use the 5x5 model to do so, and then use the 5x5 model to adapt each of the adventures as well.
To be honest, the way I've done it in the past is often more like 3x5 or 3x7 or something like that, with many of the permutations down the line not ever really defined. So specifically attempting to use the 5x5 method is very familiar to me, yet also a bit more disciplined and organized than what I normally do. What the 5x5 method doesn't really seem to offer, though, but which I think is important, is a 1x1 introduction and a 1x1 conclusion. The PCs can start driving the adventure from what the options are on the table after they've managed to get a handle on their characters, but I believe in a little bit of "virtuous railroading" at the beginning of the campaign and then I prefer to funnel them back into a conclusion.
Also; check out Dragon Magazine #429 for the most recent (and author's favorite) write-up of the 5x5 method. I'll be posting my 5x5 list/grid as soon as I've finished it up, which with any luck, will be quite shortly.