Research suggests that some students find it easier to learn words if they (a) learn them in groups and (b) make use of pictures. You can group words in any way you like — topic, grammatical feature, word root, and so on. Pictures can help you to remember the meaning.
Also, you can help yourself to learn more words and expressions by reading and listening to as much English as possible. Here are some ideas about things you can read or listen to:
· Academic/Professional literature
· Sports reports
· Conversations with foreigners/native speakers
Remember that you should be always motivated, so make your choice based on your likes and dislikes.