The Plot Thickens

Moonlighting
Bruce Willis, Cybill ShepherdPlotting is tough, at least for me. I often discard something because I don't think I can develop it into a full novel. My process is a bit foggy, possibly part of the problem. The characters come first. I know them before I start. Next I try to come up with real reasons that will keep them apart-the main conflict. Just as an example, an environmentalist and a developer and the reasons they care passionately about what they do. The stronger the motivation, the stronger the conflict.
  Then I think of the main problem they have to overcome. Say she wants to build a low-income housing development in the place where the last two dodo birds live, which he wants to protect. Since I write romantic suspense, the problem usually involves a crime. So enter the villain, a greedy energy magnate (a stereotype, but okay for this blog). He wants the land because of a natural gas pocket below ground. When you give all the characters strong reasons for what they want: she came out a tenement and her sister died because of the crime/poor conditions/whatever; he was lost in the woods as a child and a wolf saved him; the bad guy has to have a strong motive too, something more than just wanting money. You have to ask why he wants money so badly he'd use underhanded or shoddy methods to get it.
MUIR WOODS© Michael Thompson | Dreamstime.com  Once you work out these things, ideas for things that could happen along the way should pop up. Of course, you have to figure out how to overcome the problems and get the characters, at least the H&H, to work out their differences and have their HEA (happily ever after, if you're new to this <g>). I'm a mix of pantser and plotter, so I don't have any details worked out ahead, but I do have a general idea. Often the plot veers unexpectedly, but that's what makes it interesting.How do you do it? How much do you plan, and does your story stay on track?