There are different point of views about wether it's easy to learn English or not. In my view, it may be hard but interesting and enjoyable. Even though certain rules are difficult to memorise and foreigners don't always understand me because of the Russian accent, I always have a motivation to study because it's impossible to imagine a successful person who doesn't speak English in the modern world, the world of international communication and interaction.Choosing what is more important — grammar, vocabulary or pronounciation is not an easy task as you can't say that you are a good speaker if you have a wide vocabulary but your grammar is not as good as it needs to be to be able to express your thoughts correctly. In my view, everything is equally important. A person doesn't need thousands of words to be able to communicate. At the same time the more woeds you know the more accurate and beautiful your speach is. At the same time good grammar is always helpful to make communication more pleasing and resultative. As for about pronounciation, it's always a sign of courtesy if you talk to a native speaker without a strong accent.I, personally, prefer speaking and listening as it improves my communicative skills and gives me an excellent practical knowlrdge.In my view, the best way to improve anybody's language is living with native speakers being isolated from people talking your own language. That's why I would love to spend a couple months in an English-speaking country.
