Just got back from a trip to japan, here's my number 1 tip.

Learn some basic Japanese phrases and words. Also learn to read Katakana.

Seriously, learning some basic Japanese was a game changer compared to my first visit where I knew significantly less. Learning Katakana especially means you can read 'english words' in japanese like 'Hot Dog' and 'Iced Coffee'. Many drinks menus are in katakana and a surprising amount of food also uses katakana in the name.

On speaking and listening though - learning at least some basic phrases like 'I want this' 'what is this' 'bill please' 'paying separate' and 'how much is this' as well as numbers means your not fumbling around most of the time trying to figure out how to communicate basic things or figuring out how much things cost.

That said, Tokyo especially is fairly accommodating as many menus use pictures, a lot of restaurants have english menus, though the prices were different compared to the japanese menus and some of them had different items available on them, the subways and busses generally use English although the further you depart from Tokyo the generally harder it is to navigate subways and busses.

Then there are the attitudes of people - generally, a lot of Japanese people were far friendlier to us when realizing that we learned some basic japanese, which actually scored us some free items at some restaurants and shops we visited, and while we couldn't have full blown conversations, knowing enough to answer and ask some basic questions helped overall with the feeling of isolation you can get when going abroad.

Now for some other useful tips...particularly about restrooms....

Be prepared for some of the worst toilet paper you've ever experienced. I'm talking 1-ply toilet tissue.

Buy or bring a very small hand towel to dry your hands with as many restrooms don't have places to dry your hands.

Bring a small anti viral hand soap as some restrooms don't even have soap in them. People just rinse their hands with water and walk off apparently.

And that's about it! Happy travels!