(As well as a (second Language)

Find native English speakers. In certain areas it's the hardest thing to do, but it's the best use of your time. Talking to actual native speakers is the most effective way to improve your English skills, speaking or otherwise. So whether you have to Skype them, call them, or beg them to speak to you, do so. Your progress will be faster this way than any other.
• Even if they're just tourists, invite them to dinner! They get a meal, you get an English lesson. Advertise on Craigslist. Take a class and get buddy-buddy with your teacher. Offer a language exchange. They're hiding out there somewhere!
Listen to the music of English. No, not English music, the music of English -- its lilt, its prosody, the sing-songy-ness of it. The intonation. Even if you speak perfect English technically, if you speak it like a robot you're not speaking it the way it's meant to be spoken.
• Watch people. Watch how their mouths form the words. Watch how emotion is communicated. Watch where the emphasis goes on certain sentences and how that provides context. Apart from just deciphering their words, take notice of the humor, the feeling, and the formality they employ.
Take different style classes. Yes, one class is good. In fact, one class is even great. But if you can take more than one class -- of differing styles -- that's even better. A group class can be cheap, fun, and work on all your skills, but adding a one-on-one class, too? You'll get that individualized attention to your speech you've been craving. That's a double dose of improvement.
• There are specialized classes you can take, too. Accent reduction classes, business English classes, tourism classes, heck, sometimes even food classes. If you see something that interests you (let's face it, sometimes grammar doesn't cut it), go for it! You may learn more than you think.
Speak English at home. This is the biggest, easiest mistake to make. You go about your day, you're on the job working partly in English, you go to your English class, and then you go home and revert back to your native tongue. While you may be making slow improvements, you'll never get past that dreaded lingual plateau. Make a point to speak it at home, too. Have only English at the dinner table. Stick to English TV at home. Make it as 24/7 as possible.
• Heck, talk to yourself in English. Narrate your actions. While you're washing the dishes, say what you're doing, thinking, or feeling. It sounds a little silly (if you get caught!), but it keeps your brain thinking in English before your first language, which is huge. Once you can do that, the rest is just keeping it up.