Good ways to learn english vocabulary are by reading english dictionaries, thesauruses and basic english vocabulary lists. While there are many ways to learn english vocabulary, dictionaries, thesauruses and vocabulary lists are the most resourceful in terms of containing and exhibiting english words and information pertaining to those words for english vocabulary holistically.
Dictionaries are one of the most important if not the most important resources needed in order to learn english vocabulary. The reason for that is simply because even when partaking in several different vocabulary activities or utilizing any method that serves to improve vocabulary, more often than not, a dictionary is needed in order to fully learn and understand the definition of newly encountered words. Unless the definition of those newly encountered words are being explained in other ways(e.g. a person explaining, the definition being adverted to within a vocabulary activity etc...), a dictionary is usually needed to thoroughly learn english vocabulary. Even compared to those alternate construals of newly encountered words, dictionaries still usually do the best job of explaining the holistic meaning behind words since not only can dictionaries provide definitions, but the different forms of how a word can be used along with sentence examples. E.g. present tense, past tense, whether a word can be used as a noun, verb, adjective etc... depending on its context.
Thesauruses combined with the use of dictionaries complement each other well and reading them of course is a very effective way to learn english vocabulary. Thesauruses can provide several of both synonyms and antonyms for words. Synonyms are words that share similar meanings to the words they are synonyms of, and antonyms are words that have opposing meanings to the words they are antonyms of. Like dictionaries, good high quality thesauruses can also focus on different forms of a word if that word can be used as both a noun or verb etc... and provides synonyms and antonyms for those different forms as well. Studying this is very important when trying to learn english vocabulary since when a word has more than one form(noun, verb, adjective etc...), it can have a completely different meaning depending on what context it is used in. E.g. I can place(verb) something on a table, or I can move to a new place(noun).
Reading, studying and becoming familiar with common english vocabulary lists is a good way to learn english vocabulary. Just like with thesauruses, the usage of dictionaries play a significant role in thoroughly learning and understanding vocabulary lists. Common english vocabulary lists would be groups of words that pertain to common english categories. E.g. Education, geography and entertainment would qualify as common english categories, while teacher, student, classroom, country, city, town, music, games and television would be words that pertain to those categories. Certain words would apply to certain categories. Knowing and understanding common english vocabulary lists is effective when attempting to learn english vocabulary since words from common vocabulary lists are words that are likely to be used and encountered almost every day.
There are a lot more ways to learn english vocabulary, but understanding basic and common vocabulary lists is good at a beginning level. Dictionaries will always play a major role in almost any method being used to learn english vocabulary while thesauruses can be used to learn even more with those same methods. That makes it evident how dictionaries, thesauruses and vocabulary lists all contribute well to learning english vocabulary.