You should look for a language school that will sponsor your pre-college student visa. Be careful because not all language schools in Japan can do this.
I can't help you much with selecting a school because it's a bit of a crap shoot with trying to pick a school without actually visiting it. I was in the same situation a year ago. I pretty much blindly picked a school and lucked out that it was pretty decent. I've met some JETs that were already here and they had the luxury of visiting a few schools for a free lesson to guage how much they like the school and pick the best one for them. Obviously that's not possible from abroad, unless you come over for a scouting trip ahead of time.
Anyways, no matter what school you pick, you need to submit your paper work about 6 months ahead of time so that they can get your pre-college student visa processed. You'll receive a Certificate of Eligibility in the mail. You take your COE to your nearest Japanese embassy (in the USA / France / wherever you are) and receive your pre-college student visa.
You'll need to arrange for accommodation. Lots of people use guest houses like Sakura House or Leo Palace as it's not so much of a hassle. Some of my friends have started out in the guest houses and moved to other apartments in the city once they've had a chance to explore a bit / find room-mates / etc. Also, some language schools can supply dorms but I don't know which ones those are.
Don't worry too much about not knowing Japanese before you get here. I didn't know much either. The schools will give you a level check on or before your first day and place you in an appropriate class. I will say that already knowing how to read and write hiragana and katakana before you get here will give you an advantage. Learning at my own pace, it took me a couple months to learn kana in the USA. But when I got to classes here in Japan, they sped through kana lessons in like 2 weeks. Also, if I had to do it all over again, I would have started taking all of my notes in kana from the beginning. The more you use it, the faster you'll be able to read and write. Using romaji will slow down your reading development in my experience.
Here's a database of language schools in Japan:
Japanese Language School Database - information about all JLSs in Japan!