EDIT: Jhony, I'm going to edit the title of this thread so it's easier for others to read.
When it comes to writing plot, I'm much more of a
gardener than an architect. But, I like to keep a few things in mind:
1) who are my characters? Anyone should be able to ask me anything about any one of my characters, and I should be able to answer AS that character. If I don't know my charaters well enough to get deep into their head space, I can't write my plot. My characters drive my plot (err, I hope. At least, mostly). Importantly, all my characters have to have flaws. If my characters are perfectly talented folks, they're not going to get into any kind of entertaining trouble. But if they don't have a good sides too, my readers aren't going to emotionally invest in who they are.
2) What are my characters' motivations? What do they WANT? How are they going to go about doing that? My characters have to remain IN character, but also grow as people as the plot progresses. If I don't know what my characters want, I can't write my plot.
3) What are the barriers in the way of my characters getting what they want? Another way to phrase this is, what is the overall conflict of the story? For example, in What it Takes, Colbey wants to find Peter. In her way are a LOT of things, including the end of the world, a disappointed almost-father-in-law, and a cancer-riddled warlord. Colbey also gets in her own way a lot, by avoiding working with other people who could have told her where Peter was a long time ago.
4) How are my characters going to overcome the barriers in their way? THIS is the essential "plot" question. The trick here is that the way they come out the winner in the conflict must be consistent with who they are, or the tools they have.
This is how I go about writing a story, but what happens in that story grows out of who my characters are. Maybe some other more experienced writers can pop in here and explain better!