1.The Virtuous Cycle
A virtuous cycle is a process through which you steadily improve over time. Think of improving your English fluency as not going from point A to point B, but, rather, like a spiral that grows over time as in the graphic. You'll start off slowly, but you'll expand, you will become more fluent, which will lead you to want to speak more and so on. The key to improving fluency is to grow slowly over time and take time for the process. It doesn't happen over night, so you need to have the right attitude: I'm going to make mistakes, and I'll learn from them.
This may seem like a simple answer, and it is! However, over the years I've noticed that students who are willing too make the most mistakes are also the students who more quickly become fluent in English.
Students who are overly worried about being correct may do very well on grammar tests, but they often have difficulties speaking English. That's because they become too self-aware and don't allow themselves to join in the flow of a conversation.
2.Conversations are a River
Good conversations flow like a river.
They go from this topic to that topic, nothing is forced. If you listen to closely to yourself, or are constantly thinking "Is this right?", you'll block the flow of the river. It sounds simplistic, but I've noticed it to be absolutely true. Even if you have difficulties finding the right words, take your time, find the words and participate. Don't criticize yourself.