What do you usually say as a formal hello?

Oh hello there @WanderingKaren ;) we are actually the same, English is not my mother tongue too but I am lucky that I was trained on how to express myself with the use of the English language.I use to work for a call center company here in the Philippines and we are assisting international clients so we are required to speak in English as the general language.I try to make it a point that whenever I introduce myself I can be heard and well understood .I try not to use hyphalluting words im sorry for the spelling hahaha i dont know if it's right hahaha so that it will be very easy for me to explain to the audience or to the person i'm introducing myself with.It also depends on the nature of why you have to introduce yourself if its for a job interview you have to be yourself express what you really like., what you really are and what you really understand.If it's for public speaking which means you have to be in front of a large crowd , you have to be creative think of ways that you're audience will remember you .Try watching more English movies or even tv shows so that you can have a better understanding on how you will construct your sentence., read a lot of english books, magazines, pocket books to widen your knowledge to some words and how you can use them to introduce yourself. and last practice everyday so that you can get used to it.

Normally just hi or hey.

English is not my mother tongue too. But I also use the english language at work. In introducing myself, I immediately say introduce my name and my purpose. It's because like you I also don't know how to introduce professionally.

I am not the "formal" type and I can't remember introducing myself during interview because the interviewer knew me already but I don't use hello even on the phone I use "Hi! I am..... "

I generally behave the way I am everything is natural