Tips for first big trip to Tokyo?

I plan on going to Japan in about 2 years. This is the first time I'll be leaving the country (I've only ever been to neighboring states).

What are some tips? Aside from the most common ones. I'll be going with 1 or possibly 2 other people if they helps.

Also, what are some stops you recommend?
I love cats and anime, so going to Gōtokuji temple will be a must for me!

And since this is my first big trip, any budgeting and packing tips are more than welcome. Same with general locations to stay.
Thanks!

by aefee1662