The key to improve speaking is, hands down, practising! The more you practise , the better your fluency will be. The best thing is , clearly enough, speaking to a native speaker so that you can not only enhance your vocabulary but also improve your pronunciation and cadence. Listening is also paramount because you become familiar with the sounds and features of the language and you unknowingly acquire new words.
Basically, doing practise regularly no matter how long it takes and talking to native speakers of the language which you want to learn always do the trick. The secret of achievement is pretty clear : Don't give up against all odds.