All I can say is believe in yourself, and talk to people. The more you do it, the easier it will become. The difficulty is all in your head~ :)

Most of the time,I can not speak English bravely,because I am worried about is not accurately express what I mean, would make others misunderstand. So... (T.T)

You can learn from a mistake. There are certainly worse things in the world than improper grammar or a misspelled word! No one will fault you for such things. We all understand that you are learning; we are here to help you. More important than speaking or writing correctly is being true to yourself. Don't just make language partners, make friends. If you meet the right people, they can be with you for the rest of your life. As far as I see it, I'd rather speak to someone who didn't have perfect grammar but who was an interesting, intelligent, and kind person than to someone who is extremely boring but has flawless speech. 你可以从中发现错误。在生活中会有一些拼写错误的词汇和使用错误的语法，但没有人会因为这些事情而责怪你。我们明白你只是还在学习。 我们将与你同在。与无误的写作和优美的演讲相比，相信自己才是最重要的！不要只是为了得到语言上的伙伴，而是要交真正的朋友。如果你能遇见对的人，他们将和你一起度过你的余生。对我而言，我宁愿和一个有趣聪明的人交流而不是只有语法运用精准的人；我宁愿和一个善良的人做朋友而不仅仅是一个会枯燥演讲的人。(Thanks to 邓星辰 for helping me translate this.)

Hi I suggest that you ask and answer some questions in the italki Answers section at the top of the page. this will give you more confidence. Good luck.