If I want to advance my English, I must have a lot of vocabulary.
But,how can I do ?
It's easy for me to forget.
Repetition is the key not to forget, but for a good vocabulary, memorizing should be the last method you should consider.
I can recommend a practical method for you to learn the names of the object which you see in everday life (at home, at the office, etc.). Write down those names on small pieces of paper and stick them to those objects. For example, stick a paper with the word "stampler" written on it to the stampler you use, to where you easily see, of course. This way, every time you use those objects, you'll see their names in English, which will be hard to forget.