Eman,
A good way to remember new words is to write them down on a piece of paper and keep that paper somewhere you look often. I keep my papers taped to the wall behind my computer. I glance at them occasionally WITHOUT EVEN TRYING TO MEMORIZE THEM. Because they are somewhere convenient, I am able to study these new words multiple times a day.
I have a friend who writes a little story once a week and tries to use all the words she's learned that week in the story. That's not something that interests me but maybe it'll work for you.
Just remember that using the word often leads to it becoming a part of your natural vocabulary.