Whether it is English or any other language, language learning is about reading foremost.
You read texts on diverse subjects, looking up words, phrases, and grammar as necessary.
In the beginning, reading serious texts will be difficult. So you need to strategize it a bit.
Find texts which have translation available in your language, and read them side by side.
You can also reread books you're already familiar with to make it easier (some people use the Bible for this).
Also get the online mouse-over dictionaries so you can look up phrases quickly when you read online.
With these aids, you just read away.
Reading good material is the best way to build up vocabulary and increase comprehension level.
Personally, I don't think you even need flashcards and other things based on isolated word lists.
Always work in context, with good texts and audio. Mix in video, live conversation as you go on.
Learners who read and listen a lot tend to reach a high level.