That's good! I have to plan things out, too. ^^ I think for the most part it's better, although apparently from what I have heard, Tite Kubo (mangaka of Bleach) just DOES things, from characters to story. He'll just draw a character, then name the drawing and start writing a background for it. Completely backwards from how we are trained to work XD
Anyway. I think your next step (if you are looking at submitting to a publisher) is deciding which publisher would be best. There are general publishers that publish a variety of genres
(such as Tokyopop, Viz (which just started accepting submissions, by the way!!), Del Ray, Dark Horse, CMX, and Yen Press), genre-specific publishers
(such as Yaoi Press, which is not currently accepting submissions, Aurora/Deux/LuvLuv, Icarus, ALC, Yaoi Generation, etc), small press publishers
(eigo manga, Slave Labour Graphics, NDP), online publishers
(Netcomix, eManga, WirePop) and also publishers that just want artists and not projects
(Seven Seas, Antartic Press).
Anyway, if you are serious about putting out a manga/comic, start planning your submission tactics; decide which story you want to dedicate your life to for the next however long, pick your top three publishers and pitch your project idea to them first, give them six weeks to respond (unless they specify some other time frame) and then continue to shop around for other publishers.
As far as independent publishing goes, for the most part, you get what you give. If you stay dedicated to a time schedule, promote yourself widely and consistently, tour conventions, and be good to your fans, then you will succeed. It does take a lot of dedication, and a lot of work; if you procrastinate, you are only hurting yourself. To me, it's worth it, which is why it's the route I am taking
It does come with problems, though, most notably the lack of exposure and promotion that comes with being published by a company with distribution power. However, I'm working with some other independent studios to come together to combat this; we're still in the idea stages, but if you're interested in learning more/getting involved please send me a message