Basically hello is translated こんにちは (kon-nichi-wa) but the japanese greetings also depend on the time of the day. In the morning you often use おはようございます (ohayou gozaimasu) as hello. When you speak to friends and family the おはようございます is often abbreviated to おはよう (ohayou). Around noon or afternoon it is こんにちは(kon-nichi-wa) and like you say “good evening” you say こんばんは(kon-ban-wa). There is one exception: If you are answering the phone you use もしもし(moshi-moshi). Other useful phrases are ただいま (tadai-ma) ( it means “I’m home”) and おかえり (oka-eri)(it means “Welcome home”).
Close male friends and relatives use おっす (oss). Female Friends or friends with opposite gender don’t usually use this informal greeting. This greeting is similar to “hey, man!” or “hey, dude!”
Another informal greeting that is nowadays quite common is よ!(yo) , よー!(you) or おう (ou), they all mean “hey”.
The phrase 最近どう (saikin dou) is often used as a greeting, which would be similar to “what’s up?” or “what’s new”. As this phrase is also quite informal you should only use it to someone you are on familiar terms with, like a friend, relative, classmate or co-worker.
Another useful phrase is 久しぶり (hisashiburi) which is used to greet someone you have not seen recently. In English this greeting would be “long time, no see” or “it’s been a while”. A more formal way to express the greeting would be お久しぶりですね(o-hisashiburi desu ne).
This video is very useful to learn the pronunciation of おはよう、こんにちは and こんばんは. The video could be quite a challenge since she is only talking in japanese but I think it is a very good way to learn a language by speaking just the language. So give it a try!