I've read a really good tip on website. You know that guy Benny Lewis? He calls himself "Benny the irish polyglot". Well he wrote: "Everyday I go for at least 500 mistakes. If at the end of the day, I havn't made 500 mistakes, it means I haven't spoken enough..." I think it the best tip I've heard, because it kinda relieves you of the stress of thinking you have to speak perfect and flawless..