There are several ways for building vocabulary. Some are better and some are worse. Some are even harmful!
Here I will share with you some important
guidelines, and also some words of caution.
Now, what if you want to learn a new language?
You start by understanding the meaning of a word, and then you practice using it. In the end, you KNOW it. This is the way for building vocabulary.
Let's have a look at a real life example. You learn a new word. For example, the word "a".
What does the word "a" mean? A dictionary is a good place to check this.
You will basically find out that the word "a" means you are referring to 1 thing, which is not specific.
OK! Now, let's use it! "a dog" would mean "1 dog, any dog". "a cat" would mean "1 cat, any cat". "I want a hat" would mean I want 1 hat, and I am not saying which one.
Now you can practice using the word by making up sentences. You can practice speaking it, reading it, writing it, drawing it, playing games with it, anything goes!
At the end you can be quite surprised when you see how well you know this word.
Do that with many words, and you will know many words!
Keep doing that and there is almost no limit of how far you can get! I said "almost" because at some point, you will discover that grammar is also quite important. I mean, words are important, but you need to know how to combine them correctly, too. "drinking the can" and "canning the drink" (preserving the drink in a can) mean entirely different things, don't they?
Language world: you take a lot of English lessons. You dedicate time and money. You learn special tricks. You go to the exam, you pass the exam. You get your nice score. Great. Do you remember any of it now? Can you use English in your work place? Can you use it when you travel? Can you easily read an English website and understand it?
Conclusion: exams and tests are there to verify your knowledge. They are not the end product. They can get you some nice pieces of paper, but you will not become a more skilled person because of your score. Find out what is your real purpose and always keep it in mind.
Language world: your teacher gives you a list of 20 new words. You write them again and again in your notebook. You really memorize them. But you don't actually use them. Now you are in New York, trying to have a conversation. How much benefit can you get from those words? Not much, I can tell you that.
Conclusion: information is all well and good, but it doesn't help you much unless you practice it and unless you can use it.
Language world: your teacher tells you that the new word you are going to study today is "chukubuku". You start singing songs about it, playing games with that word, and reading stories that have this word. You get no explanation about what this word means. Or, you do get an explanation, but you don't actually understand it. Big, big mistake. A very bad way to learn. (By the way, "chukubuku" is an invented word!)
Conclusion: understand the explanation before you start practicing. Practicing will definitely increase your understanding, but if you practice with no idea behind it, that won't really help you.
One last important tip.
Here is an example: a student reads the following sentence: "Marta has a parasol." Hmm… OK, what does that mean? You can guess all day long, but that won't necessarily get you to the right answer. You will probably remain unsure. But this can be easily solved. Simply check what it means! You can use the dictionary. "Parasol" is a kind of umbrella that protects against the sun. Ah, now it makes sense. "Marta has a parasol."
Another example: my English teacher taught us there were words you had to understand, and other words which were not so important. So we shouldn't waste our time on understanding the less important words. We should kind of guess them.
I was actually doing just that for a very long time. It made me think I knew words, when I knew them wrong.
For example, as a child, I ran into the word "respect". It was always mentioned in "serious" contexts. So I concluded it had to do with seriousness. In my mind, if it was said that someone respected someone else, it meant he looked seriously at that person. Boy, was that inaccurate!
Later on, when I "bothered" and opened a dictionary, I discovered I had completely invented that meaning. The true meaning was "to treat someone or something in a polite way because you consider them important". Do you see the difference from "seriousness"? I sure do!
So why is understanding words from context false help? Because it seems like it helps you to study faster, not stopping on every unknown word, but it actually creates damage.
In summary, the way to build vocabulary is to learn vocabulary - not to guess at it!