if your a student try finding tickets for students.
they generally cost less i use
JTB USA for cheap filghts to Tokyo
some times around 1000 less then normal plane tickets.
Before you go buying your ticket you want to make sure you have living arrangements.
you can try guest houses or hostels or cheap short term apartments.
I use Sakura House * just google them*
they have apartments/guest houses/ and hostels all over Tokyo.
book your living situation and then make sure you work out the time difference with plane ticket so you know when you will be arriving in Tokyo Time.
it really depends on how long you stay.
i go for 3 months at a time and get apartments
for shorter trips you might wana try hostels or guest houses.
hotels can be very costly, and some will only let you stay a few weeks.
i recommend traveling with a friend.
makes the trip more enjoyable.
g'luck