Learn some Japanese! Below are some expression to use during a travel in Tokyo. They might be not the most polite vocabulary, but they're what real Japanese said in daily lyfe.

All Q&A are based on my real conversation during the trip :)) Most of the time I know what they're talking about from the intonation, gesture and the condition, but I couldn't know how to respond in Japanese! haha that's awkward.


Another tips for you when you really need to ask strangers about directions, etc, and you don't know how to ask about it in Japanese, just let them answer in Japanese. Maybe they're understand your question in English, but do not know how to said in English. Also many Japanese are kind enough to try to talk in English for you..

Sumimasen: Excuse me / sorry.
A Japanese I talked to in Shibuya said, DON'T overuse sumimasen it's irritating for most people! :)) Also, read it as suimasen to make it smooth.
Shitsurei / Gomennasai: I'm sorry. 
Hai / Un / ii yo: Yes / Alright
Iie / Iya: No
Tabun: Maybe
Sou desune: That's right / correct
Iie chigaimasu: No / false / different
Chotto: Little / a little
Doumo / arigatou: Thank you
Yukkuri, mou ichido itte kudasai: Please say it once more slowly
Ano... : Um...
Eki: Train station
Otearai: Toilet
Chikatetsu: Subway
Tabemono: Food
Kippu: Ticket

Language
Eigo shaberemasuka? [Can you speak English?]
Chotto dake desu / Sukoshi dake desu [I can speak (the asked language) a bit]
Nihongo shaberenai [I can't talk Japanese]
Japanese OK [I can speak Japanese]

Finding nearest train station & direction
Q: Ichiban chikaku no eki wa nan desuka? [what's the nearest train station?]
A: Shinjuku eki [Shinjuku station]
Q: Are wa doko? [where's that]
A: Koko kara, massugu iku.. Tully's Coffee de, hidari. [from here, go ahead.. turn left on Tully's Coffee]
Ichiban chikaku: The nearest
Eki: Train station
Massugu iku: Go ahead
Hidari: Left
Migi: Right
Hidarigawa: left side
Migigawa: right side
Eki no tonari de: beside the station
Koko: Here
Soko: There
Kore: This
Are: That

Opening conversation
Q: Doko kara? [where do you come from?]
A: Indonesia kara kimashita [I came from Indonesia]
Tokyo ni mikka, iteimasu [I've been in Tokyo for 3 days]
Hajimete da yo [It's my first time]
Senso-ji, Disney sea, to Harajuku itta [I've been to Senso-ji, Disney sea, and Harajuku]
Tanoshii desu [It's fun]
Q: Tsukareta desuka? [are you exausted?]
A: Iie, betsuni. [No, not really]
Kyoto ni ikitai [ I wish/want to go to Kyoto]
Tips: Personally I don't really like to do introducing each other name when starting a conversation with strangers, just enjoy the chat.

Eating
Q: Kore wa nan niku? [what meat is this?]
A: Sore, gyu-niku [that's beef]
Q: Ja hitotsu kudasai, ikura desuka? [ok then, please give me one, how much is that?]
Q: Sugu ni tabemasuka? [you wanna eat this here?]
Q: Tabe, arukimasuka? [you wanna eat this while walking?]
Madogiwa no seki o onegaishimasu [please give us the seat near window]
Okawari: please refill (for freeflow drink or freeflow anything)
Kore, mou hitotsu o kudasai [I want one more of this]
Tabehoudai: all-you-can-eat style
Asagohan / Chousoku: Breakfast
Hirugohan / Chuusoku: Lunch
Bangohan / Yuusoku: Dinner
Hitotsu - 1 Futatsu - 2 Mittsu - 3 Yottsu - 4

Shopping
Q: Kore wa nan-desuka? [What is this called?]
Q: Nanika osagashi desuka? [What are you looking for?]
Q: CD ga arimasuka? [Do you have CDs?]
A: Kashikomari mashita [of course]
Kore ni shimasu. [I'll take this]
Chotto misete kudasai [Can I look at it for a moment?]
Chotto miteiru dake desu [I'm just looking around for a moment]
Daijobu desu: to say when you don't want to buy things offered to you, literally means I'm fine
Sore o misete kudasai. [Please show me that]
(Akai) no houga ii [I prefer the (red) one]
Saizu ga wakaranai kedo [though, I don't know what size (to choose)]
Ii kaori [smells good (in food, tea, or anything edible)]

Watch Japanese anime or drama are a quite fun & quick way to learn. Just remember anime and dramas are exaggerated, copy them directly will make you look stupid.

Or, you can read these articles:
10 Japanese Words You Need to Know Before Traveling to Japan | japan-talk.com
11 expressions to apologize in Japanese | japan-talk.com
Key Japanese for travelling in Japan | cheapojapan.com
100 phrases to memorize before traveling in Japan 

First timer tips:

• Tokyo people are generally quiet. Lower your tone when talk in public space. Don't be too loud in general.
• In Tokyo, use left side of escalator. Right side is for fast-moving people. In Osaka, the opposite.
• Always take queue for anything including getting on the escalator
• Using elevator on the subway is not nice. They are considered for elderly, disabled, and expecting moms.
• Most indoor of places in Japan don't allow you to take pictures, look out for sign or ask the security first.
• Try to not checking your phone when you're in the priority seat area
• Your PASMO / Suica card could also be used at vending machines
• At every place you visited, go to their bathroom/toilet just for the sake of fun. Japanese toilets are often crazy lunatics, just saying.
• Take your guesthouse address card & bring it anywhere. Don't afraid to getting lost
• Ask direction or help in general to police box (koban) they're available on any train station & subway.

• Free wi-fi is not a common thing in Tokyo, I suggest you to buy b-mobile visitor SIM card (3,980 JPY +tax for 2 weeks flat or 1GB data) or rent a wi-fi device. Harajuku station, Yodobashi-camera front in Akihabara, Haneda airport (free for 1st 2 hours), most of the Kyoto bus-station are places I know with free wi-fi. Here's 10 wi-fi cafe within 10 min walk from Shibuya station. And, you could be happy that Tokyo is adding free Wi-Fi to 143 subway stations for foreign travelers.
• In Japan it's habitual to take off your shoes before entering indoor space. Just in case you're not accustomed to.
• There's a thing called Kasapon or, umbrella condom. Many department store have kasapon near entrance, use this on rainy days so your umbrella won't drips on their floor

• Japanese languange actually use handful English vocabulary, only, they say it in different accent. Try to speak slowly.
• Shops are opens late and closes early (mostly 11 AM to 8 PM), if you plan to explore more than 1 place, make sure you have time for it.
• There's many coin lockers spread throughout Tokyo,  most of them available at train/subway station. Don't worry about carrying too much goods after shopping, put it in coin lockers and you could have another go. Usually cost 100 JPY, or up to 500 JPY depends on the locker size.

• You could change money bill into coins at any station master (they are beside the ticket gate).
•  If you're trying to go to certain place, be sure to check all the floor! Tokyo grows very fast and many stores/venue jammed to one building. Some great places are hidden on the basement.
• Be careful when you need electricity to charge your gadget, in some public place, you may be accused of electricity stealing.

Useful articles:
Travel tips for Tokyo | mcha-jp.com
101 thing to try in Japan | japan-talk.com
Tokyo official guide | GO TOKYO
Tokyo guide | Tokyo Scum Brigade
Tokyo tour guide | Tokyo Damage Report