There are countless ways to greet someone ranging from gangster to meeting the president. With such a large range you can rarely go wrong with "hello". If you say "hello" you rarely will insult someone. I'd stick with that until you are able to discern the subtleties.

Hi how are you doing today?- Hola como tu estas hoy? Allow me to introduce my self.- Permiteme introducir mi Hello my name is- Hola mi nombre es