Not too bad Mais ou menos Myze oh menush – lit. “more or less.”  Use this response if you want to indicate that you are a little ‘under the weather’.
 
Pleased to meet you Prazer Prazair – lit. “pleasure.”
 
Very pleased to meet you Muito prazer M[ng]wee[ng]tu Prazair – lit. “much pleasure.”  The word ‘muito’ has a very nasal sound, which kind of breaks the rules of pronunciation!  Sometimes it can sound more like ‘moitu’, depending on the accent of the speaker.
 
Good Morning Bom dia Bom[ng] deeya – lit. “Good day” – a slightly more formal greeting than Olá – generally used up until about 1pm.
 
Good Afternoon Boa tarde Boa tarde (after about 1pm)