It was such an experience, I can't even tell you. I took so many pictures!
I have a few of them up here:
I'll post the rest when I get back to the States.
Go to the Tokyo Big Sight English page. There's a fantastic map of the subway system to get you to the Big Sight. It's saved me a number of times.
Know Japanese. LOL Ok I didn't, but it helps a lot! Thankfully they do have an International Office, with someone there that speaks English to explain how everything works. Unfortunately, it's tucked away in a tiny hallway.
If things don't change next time and you want to cosplay or just take pictures, go to the 4th floor in West Hall of the Tokyo Big Site. There will be a cosplay area and a cosplay registration and changing room.
Pay 600 yen to get a booklet that lets you enter the cosplay area outside. There's also a changing area in the building.
Learn how to change in a 1meter by 1meter square. LOL! I'm serious, that's your designated changing area. Bring everything that you need, mirrors, makeup, etc. I didn't have a mirror, so I used my digital camera to make sure my wig was on straight. X-/ Oh, and I hope you're not modest, because there's nothing dividing these 1x1 meter squares from the rest of the changing area. The area is divided into female and male though.
However, some of the "men" in the changing room, I could have sworn on all that is holy, that they were women. Only the fact that they were in the men's changing room proved me wrong. 8-O
You have to take everything with you. There is no locker or any place to store your stuff. You're also not supposed to arrive in costume. You have to change there. So get one of those small rolly luggage things like all of the other Japanese cosplayers do. :) I made the mistake of using a duffle bag. That thing got heavy really quick. 8-/
The cosplay area is outside, unless it's raining or snowing, so be prepared for cold weather. One poor Cutie Honey cosplayer had to stop posing to put on her jacket. I don't know how the girls in skimpy outfits did it. 8-/
The cosplay times (if it doesn't change) is 10am to 3pm. They clear out the cosplay area at 3pm.
You can only take pictures of cosplayers in the cosplay area.
Hmm... I think that's it. Those are some of the things I would have liked to have known before I went. But hell, it was an adventure either way. :D