|Nice to meet you||Hajimemashite||はじめまして|
|Good Morning||Ohayou Gozaimasu||おはよう ございます|
|Good Evening||Kon Banwa||こんばんわ|
|Good Night||Oyasumi Nasai||おやすみ なさい|
|How are you?||OGenki desu ka？||おげんき ですか？|
|See you again||mate ne||またね|
|Nice weather isn' it||ii tenki desu ne||いい てんき ですね|
Ohayou Gozaimasu is the polite form. Simply Ohayou is the casual form
Oyasumi Nasai is also a polite form. Simply use Oyasumi for the casual form.
Incidentaly, Nasai is often used by females after the verb stem to indicate a command.
e.g. A mother talking to a child that is taking too long to east may say "Tabenasai" - Eat your food !!
From the verb Taberu - to eat.