The first Japanese words foreigners need to learn should be greetings and social terms. The most commonly used greeting words will be “Ohayou” (Good morning), Konnichiwa” (good afternoon), “Konbanwa” (Good evening), “Sayounara” (Goodbye), etc. The next most commonly used words would be words “Arigatou” (Thank you), “Douitashimashite” (Not at all), “Sumimasen” (I am sorry), “Hajimemashite” (How do you do?), “Yokoso” (You are welcome), and so on.
“Doumo” is a very convenient word. It is generally used to emphasize a meaning such as “Doumo Arigatou” (Thank you very much), or “Doumo Sumimasen” (I am very sorry), but it can be an abbreviation of these words. When you say “Doumo” as an expression of thankfulness, it means “Doumo Arigatou,” and if you are expressing an apology, it means “Doumo Sumimasen.” When you say “Doumo” to a person who you are meeting for the first time, the person will understand that your words mean “How do you do?”
On the other hand, “Sumimasen” can be either an apology or an expression of gratitude. When you fail in something and say “Sumimasen,” it is taken as meaning that you are sorry for it. When someone is kind to you and you say “Sumimasen,” then it is taken as meaning that you are thankful. It can also be used as a request such as “Excuse me.”
It is also recommended that the following words be learned: “Kirei” (pretty),” Kawaii” (cute), “Subarashii” (wonderful), “Oishii” (delicious), etc. However, there are many foreigners who pronounce them incorrectly, ie: “Kirai” (dislike) instead of “Kirei” (pretty), or “Kowai” (awful) instead of “Kawaii” (cute). Incorrect pronunciations of certain words can make people laugh because they take them as a joke. Finally, the most necessary words for an English-speaking foreigner must be “Eigo ga hanaseru hito wa imasenka?” (Is there anyone who can speak English?)