Who's gonna help me with my English?

I'd like to get better English vocabulary skills! I'm looking for someone who could teach me expressions a native speaker would use too. I can make myself undersandable, but I think sometimes my English doesn't sound very natural. I'd prefer air-mail exchange as I'm not just looking for someone to help me but also for a good and interesting friendship. My name is Akira (female), I'm 29 years old and living in Japan. I could teach you German or Japanese.