What are the characteristics of an American accent when speaking Chinese? What advice would you give to avoid the most problematic mispronunciations?

As a native English speaker learning Chinese, I'm curious what Chinese-speaking Americans sound like to Chinese people. I've seen examples such as Mark Zuckerberg and John Cena, and many Chinese people say they sound strange. I want to learn more on how I can be better understood when speaking Chinese, assuming I have the vocabulary.