I want to start this off by saying that while I do a lot of writing on my own I am not a professional just yet, and so I am not really the person to go to for teaching anything. I just got to thinking, and figured I could reply and we would talk it out and maybe you would get somewhere. And maybe I'll get some insight that will help further my own current efforts.
Anyway, first and foremost, I would say, you need to think about your feel and your premise. Those will inform the rest of the project. Well, actually, first off I would say you should consider and maybe list all of the concepts that make you want to do this at all. What characters move you, what type of world do you want to explore, or what scenes do you just have to include somewhere? Thinking about those will help frame the rest of the story, as you will be putting together a world to let you use those ideas.
Back to tone and concept, though. Decide whether you want a humorous story, a dark one, high adventure, or whatever. And decide on themes. We already have part of the concept in that its a team of transforming superheroes, right? Well, what makes them transform: magic, science, biology, or something else? What kinds of things is the armor based on, and what about the monsters? This is important because it helps tie the setting together. Den-O had all that stuff with the trains, Kiva had those monsters, etc. You can expand out from there to ask what sort of world would contain these things, or come to them by deciding on the world.
As you may have guessed by now world building is where my brain tends to go first. It isn't that way for everyone, but how your world works is an important part of putting together what happens in it. If you know you have, say, technological armor with an angelic motif, then a hyper-advanced society or organization with a grand mission of either world cleansing or chaos and fire isn't that hard to figure out. Characters like, say, an oracle hooked up to a giant crystalline computer system or a flawlessly beautiful but arrogant and insane 'boss level' villain follow along easily enough.
Of course, you can always start with characters. What kinds of personalities would you like to give your heroes and villains, and what sorts of conflicts interest you? A broken, brooding man might not fit a bouncing bubbly magic-we-have-to-hide-from-mom setup as well as a grim corporate apocalypse run by elderich abominations in the guise of business and political leaders.
Then there are the plot and theme ideas. Do you want huge battles against planet destroyers from space, where the heroes are needed because no one else can fight this battle? Grim battles for the souls of the forgotten, fought in back alleys against creeping shadow things that feed on the lost? Whatever you want, you need to make sure you have characters who would end up in these situations and worlds where they make sense.
Really, what you should take from this is that every aspect should affect and alter the others. In the most successful of stories nothing is wasted - they all make the whole story better, fuller. Everything has to mesh well, and you will need to avoid cliche and retreading old ground. This brings us back to the original suggestion of listing what you want. Once you have that you can start putting together a world and a plot to contain all of the ideas. You have to do a lot of brainstorming before you can really get started. Once you have a feel for the world and what's going on in it you can work on an outline of the overall story of your series, then start developing and refining it so you can write your serial fiction or whatever.
I hope that helps get the conversation started, at least.
