I believe vocabulary is the most comprehensive and most difficult aspect of English for foreign learners to master thoroughly. They should concentrate first on learning the most frequently used and therefore most important English vocabulary for their practical real life needs.
Multiple sense English words and synonyms (words with a similar meaning) present special difficulty for foreign learners. Other difficulties with learning and using English vocabulary include fixed word collocations, phrasal verbs, idioms, proverbs and regional differences in vocabulary usage. There are differences in English usage in English-speaking countries in terms of spelling, pronunciation, vocabulary and grammar. I know some specialised books dealing with British and American English differences.
English usage can also be formal and informal. Formal English is the language of the mass media, education, business, economy, commerce, technology, science, etc. Informal English includes colloquial, slang and dialect usage. It is harder for foreign learners to master informal than formal English vocabulary.
Thematic general English dictionaries combined with English synonym dictionaries are a valuable tool for mastering English vocabulary logically, comprehensively and intensively for real life needs of learners. Extensive reading on a variety of topics is another effective method for expanding English vocabulary knowledge by learners of English.
Of course, English vocabulary is somewhat difficult for beginners to learn. You can still overcome by reading more passages or even reciting a number of new vocabularies everyday. However, grammer is relatively hard to learn when comparing to vocabulary as different languages will have different usage of words and sentence structures.
I am a former English as a foreign language teacher. I have created several really practically special helpful articles on learning various aspects of English as well as an extensive list of English learning resources (books, websites, audio and video aids).
I'd like to know your opinion about them and to exchange information with you on those issues.
I do not promote or advertise anything. This informative project is intended solely as exchange of information for the purposes of knowledge improvement and idea production for learners and even teachers of English which can help them in their English activities.
As you know there are a large number of aids (books, websites, audios and videos) for learning and improving English. I have already explored this issue on the Internet quite extensively to create my special list of those resources. Perhaps you could express your opinion about what aids, what courses and why you regard them as the best ones for beginning, intermediate and advanced levels of English. What articles and websites on issues of English are the most helpful and useful for learners and teachers of English?
Discussions and exchange of information could be mutually beneficial to us. Do you think there are issues of English that we could discuss and bring to the attention of people interested in English?
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If English learners initiate their "English learning journey" by reading newspaper, the efficiency will indisputably be lower, since newspaper does not only concentrate on vocabularies, but also the grammar. Sometimes, even though they put two simple words together, it can be bewildering. However, the journalists have rather accurate English, so it is more reliable for beginners to learn this language by reading newspaper after they have known ample words and have good bases for grammar. Then it will be easier for them to understand the meanings and even derive new knowledge.

The issue that may be intriguing for beginners is that while there are innumerable vocabularies which have similar meanings, they are different in reality and definately not identical.

Extensive reading in English with the help of a good English dictionary on a variety of real life topics is one of the ways to learn English vocabulary. Since there is an enormous amount of reading material in English, a learner of English has to prioritise reading in subjects according to learner's needs for using English to encompass first the most neccessary, relevant and frequently used vocabulary. Day-to-day topics ought to come first in reading.
Learners can master the most important English vocabulary by reading thematic texts (materials), first of all on everyday topics with important content, for example: Practical Tips and Advice to Make Everyday Life Easier and Better (practical solutions for everyday problems). Such self-help books on settling everyday matters are available at book stores.
In addition to thematic texts (materials), learners can read thematic dialogues (samples of real life conversations between people), narrative realistic stories, fine literature, newspapers, magazines,
Internet materials, books in various subjects, general thematic English dictionaries, etc.
Good general thematic English dictionaries arrange vocabulary by subject matter (topics) and provide clear word usage explanations and also a few usage sentences for each word meaning, which is especially important.
Good public libraries have a wide selection of English reading materials.

Learners must write down unknown vocabulary in whole sentences. It is essential that they practise telling the content of the texts that they have read. As people say, practice makes perfect.