how to overcome the stress

I have been to Iowa for almost two months, but i still cannot communicate with native speakers very well. The most stressful situation for me is when i talk with someone, who totally cannot understand what i am saying. This thing is quite often for everyone of us, and especially for me. Whatever how much vocabulary I learn, I cannot use them in the correct ways, and I cannot pronunciate them well, because English is not my mother language. However, I get some experiences about how to overcome this stress. The most important thing is think about the sentences you just say, make sure the words in the sentences are quite correct to use, and if they still cannot understand, try to use different words, or give them some examples to illustrate what you are going to talk about. Therefore, by using these methods, a native speaker will probably understand what you are saying, and after that, make sure that you need to ask him or her how to say this meaning correctly, that will give you a lot of improvement on English.