I have the same problem since I am trying to learn Japanese. Two things that helped me are using a flashcard app, and listening to a lot of Japanese. If you have a smart phone, you can use an app called Quizlet to make your own flashcards. It will test you on the words you get wrong the most, so this helps a lot. Aslo, try and find some English to listen to every day, even if you don't understand it. This will help you get used to the sounds of real life English, and you will slowly start to recognize the words. "This American Life" is a good podcast you may want to try for listening. And, here are some corrections of your questions: "How can I improve my vocabulary." "I can't remember new words." I hope this helps. Good luck!