What's the secret of successful language learning?
I think the most important thing is that you really have to want to learn the language - without that, you won't get very far. You also have to believe that you wiil do it...imagine yourself using the language confidently, and think, "Yes, i can do that."
The other thing is motivation. You have to be ready to study grammar, read a lot, listen to English songs, radio, and TV and what's more you have to do these things systematically. It is so easy to forget what you have just learned...that's why i needed a teacher to force me to study. Even the most motivated students need that extra push sometimes. I believe that only a very few people can learn English on their own.
Then there are other things: Of course you need to work hard, but at the same time you need to enjoy it and not get frustrated when you feel you're not making much progress. And you have to be realistic - learning a language takes time, and you can't expect to know and understand everything in a few weeks!
Last but not least, you should try to "develop an ear" for the language - not only to recognize the sounds of the language and to understand what people are saying, but also notice the exact words and phrases that people use...and then try to use them yourself. Some people can do this naturally, but others have to learn how to do it. So try to the best of yourself and you'll succeed.