Hi, thanks for your message!
Well, it depends on how long you are gonna stay in Tokyo for how much you can do here.
There are so many things to do and see in this city, so if it's a short trip, then it'd be better to make a wish list, but if you have time, then it'd be also nice to just walk around and get lost in the busiest city in the world.
The key of successful Tokyo trip is to learn and get used to the train system as soon as possible so you can go wherever you want to go. There are many informative sites on Tokyo, but I recommend asoboo.com the most. If you are interested in art, then www.tokyoartbeat.com would be the best website for getting information on art exhibitions in Tokyo.
I hope you'll have memorable time here!
Mari