How do you do?
には
How do you do?

仕事を聞いている
What do you do?
には
Oh, I work in IT. What do you do?

今日何をするのかを聞きたいのであれば
What did you do today?
What Will You Do Today?

最近を聞きたいのであれば、現在進行形
What are you doing these days?"

How are you？
How are you doing?
には
I am doing well
very good

Hows going?
には
Hows going?

Whats up?
には
Whats up yo-

こんな感じか