Common expression

こんにちは

It is pronounced as "kon-nichi-wa". This is used when you greet someone in the daytime, not in the morning, not in the evening and night.

おはようございます

It is pronounced as "Ohayo-gozaimasu". This is used when you greet someone in the morning.

こんばんは

It is pronounced as "Konbanwa". This is used when you greet someone in the evening and night.

ありがとう

It is pronounced as "Arigato". This means "thank you".

ありがとう　ございます

There is more polite way to say "Thank you". It is just put "ございます" at the end of "ありがとう". You can use this for your boss in your company and strangers(people you met at the first time and you don't know well).

どういたしまして

It is pronounced as "Doitashimashite". This means "You are welcome".

すいません

It is pronounced as "Suimasen". This means "I'm  sorry" or "Excuse me".

はい

It is pronounced as "Hai". This means "Yes".

いいえ

It is pronounced as "Hai". This means "No".

いくらですか？

It is pronounced as "Ikura-desuka?". This means "How much?".

分かりません

It is pronounced as "wakari-masen". This means "I don't know".

さようなら

It is pronounced as "Sayonara". This means "Good-bye".