Where to go Vietnam, Indonesia, Malaysia...?

I've spent the past year researching just about every Asian, Central American, European, Middle Eastern, North America South American country trying to find a place that best fits the experience I'd like to have teaching English as a foreign language and the travel opportunities and cultural experiences it would expose me to.

All I really want it to be away from the big cities and fast paced life. Be surrounded by natures hidden gems, immerse myself into different cultures and open myself to new opportunities. But the more time I spend trying to find this place, the further away I seem to get.

I'm not doing this for the money but would need to be making enough to get by and most of the best opportunities seem to be volunteer work which costs you a ridiculous amount of money that get's paid to an agency and not even the cores?!?!

I've never traveled overseas and as a female that would be traveling alone unfortunately I have to take safety into consideration. At the moment Vietnam seems like the perfect place, stunning scenery, friendly community, rich culture. 

If anyone could share some advise or personal experience with me it would be greatly appreciated. Maybe even another country I should be considering...