If you find it difficult to remember the meaning of a word write it on a card - then look it up in a dictionary, on Wikipedia or Google and copy out (with pen and paper on the other side of the card) a few sentences that you find relating to the word.
If you are asked to give a presentation, try to choose a topic that interests you.
Once you have reached a good standard of English, one of the best ways to learn more, is to teach and help other learners.
A forum on the internet is a place to ask questions, share knowledge and thoughts.