The best way to learn and retain vocabulary is to stop trying to learn “vocabulary”.
Or at least, not as the main thing you do.
Let me explain. Even native speakers only use around 2.5% of the words in English. And for the vast majority of people learning English as a second language, more, more, more words won’t help at all.
Neither will just learning more in the same way help you retain what you learn.
The big difference between people who are intermediate in English and people who are advanced (and beyond) is that they’ve learned to CHUNK their English well.
If you don’t know what this means, I’ve got a free training here that will teach you everything you need to know about improving your English past the intermediate stage (including “chunking).
In a nutshell, though, we used to think native speakers had grammar rules in their head, and that they combined these with words to make sentences… but this never made much sense. Speaking like this, we shouldn’t be able to speak fluently because the brain’s RAM (working memory) simply isn’t that good. Using grammar and words, we’d speak slowly and awkwardly (like most non-native speakers who have learned to speak in this way). Also, we shouldn’t sound natural simply because most “grammatical” English isn’t natural – “make a picture” is grammatical, and so is “let’s try it”. But both sound awkward (we say “take a picture” and “let’s give it a go”.
This is because native speakers speak in chunks.
So if you also want to speak in an advanced, native-like way, that’s how you need to speak, too. And the easiest way to do this is to learn in chunks right from the beginning… not individual words.
This also makes retention much, much easier.
The reason you forget things is because your learning is too shallow. You probably memorise a word, with a translation in your native language… and that’s it. But the brain has nothing to connect that word too, so it’s lost.
Learning in chunks helps you to integrate what you learn deeper into the network of your English.
Anyway, this is getting long.
As I said, I have a free training here that will show you how to do everything I’ve talked about here.