Setting clear goals is the first step to be succeed in English learning. Sometimes I feel stuck. For example, it seems that I achieve nothing even after I read a book. On the other hand, there are still so many things that I don't understand.
How do you overcome intermediate level in English learning?
What are your explicit learning goals? And do your goals work?
The English language can be very difficult as there are so many grammar rules and sentence structures. But as Doug mentioned, when you find a word you don't know, write it down, learn the meaning of the word and try use it in as many sentences as you can. As for grammar and sentence structure, constant practice is key! Once you fully understand a certain meaning or grammatical structure of a word/ sentence it will be easier to use. The most important thing is to try and talk to someone in English as much as you can, even book a lesson with a teacher just to have a conversation about any topic you enjoy. As you start to talk more and more each day certain rules of the language will become more clear to you.
Also remember, learning beginner English is a big achievement as you start to learn new vocabulary and start to become familiar with the new language you are learning. As you learn all the new vocabulary you start to feel as if you are progressing and developing your language. Once you know the basics of a language and can start putting sentences together you start reaching the more difficult phase of language structure and this is where you start to feel stuck. There is a lot more structure and development involved in achieving intermediate English. Don't feel as if you are not learning anything. You are! Keep motivated and keep learning, you will start to feel more comfortable as you practice more and will start to achieve all your goals.
I hope this helped. :-)