You need to ask yourself why exactly you are worried. For example, you might be happy with your writing, but worried about your reading. When you identify the problem, you need to do something about it. There are lots of books with practice papers. You could try doing those. I think the key to improving your language skills is practice, and working on your weaknesses.

You can get a lot of good tips from asking questions here. Because we don't know you, it does help if you can identify very specific issues and ask specific questions. Good luck!