My experience is that you don't. Ecuador is a lot of fun.

That said, you should always be careful. In Ecuador, particularly in Guayaquil, be careful what taxi you take. Make sure it has a meter, and if possible use a radio dispatched taxi (i.e. call). Beyond that, it's like most places you're likley to visit: Stay away from "bad" areas late at night, be aware of your surroundings, etc.

The only foreigners that I constantly see getting themselves into trouble are those who deliberately come down here to do the things that they can't easily get away with in their own countries.