It's simple. Believe in yourself.
Talk to a clerk at the store. Call a friend from class to talk on the phone. Find a volunteer conversation partner through a local nonprofit or religious organization. Join an adult English class in your community. (Many of them are cheap or free.) Join iTalki or MyLanguageExchange and find a conversation partner in exchange for giving lessons in your native language. Work with a private tutor to build your confidence. You can even talk to yourself in English out loud for 10 minutes a day! (No one will know or laugh.)
Set aside 15 minutes a night with your roommates, husband, or wife, and speak nothing but English. . .even if the other person doesn't understand what you're saying. My daughter is learning Spanish, and I talked to her for a few minutes yesterday in that language, using lots of body language to help her understand that I was telling her to get her coat, put on her shoes, and socks, and get ready to go. She is four, but she understood everything I was telling her because I was pointing at my shoes and socks, etc.
Record yourself speaking English, and then listen to it. I know this sounds crazy and embarrassing, but it is a great way to identify your own errors. Record yourself again on your computer, smart phone, tape player, etc., and listen to how much you've improved. Time yourself speaking on a topic to see if you can speak faster if you tend to speak slowly.
If you're about to take the IELTS exam, in addition to working with a teacher to help you do well, try these tips: