and I'm :)

thank you both, but how to practise? with bookS? myself?

Try to talk to people using English that way you can have more time to practice.

Keep practicing. But if you forget, don't worry too much about it. It's like playing tennis. If you haven't played in awhile, you might feel a little stiff when you start playing again, but it'll all come back. Of course, you need to be practicing your English all the time in order to keep improving.