Writing
Try keeping a diary; write something in English in it every day, even if it's very simple. Start with small sentences and make them longer. Again, the Internet is a great way to help. Try to friends online, visit chat rooms, forums, or post comments on blogs. These are all useful tools for you to learn well from.
Writing gives you a good chance to review words you have learned in the past, and allows you the time to think about grammar as you write. Go back and review anything you might have written in the past when your English was at a lower level, and try to find any mistakes you made.
Think about writing a short story or even a poem. If you have a teacher, he or she will be happy to check it for you.
Goal
Set yourself a goal and keep it in mind, it will motivate you to learn. For example, think about why you started to learn English. Do you need to learn English, to pass a test, for business, to travel or to watch movies? Whatever the reason, you'll find that you work harder when you focus on a target. Choose a goal that you want to achieve and then create a time-frame to achieve it by. Plan what you want to be able to do with your English ability by this time next year or in six months. Make sure that your goal is realistic and that you keep working towards it. It's worth making plans to take an English test, so you have something very real you need to learn English for. whatever you decide to do don't give up!