Always ask the person that you are speaking with to correct your mistakes.

If they do not correct your mistakes, you will continue to make the same mistakes over and over.

Making a mistake is normal.

Not correcting the mistake is a bigger mistake.

People usually tell me the same thing when we Skype but most of the time their English is actually really good. You just need to have confidence and not be afraid to make mistakes :)

I think you need to practice everyday, and have a big amount of vocabulary.

Keep practising and don't be affraid to get things wrong. 

'If you're not failing every now and again, it's a sign you're not doing anything very innovative'

Woody Allen

Just relax. I'm sure the English speaker will be very impressed at how you communicate with them. 

You can take a deep breath (to calm yourself), think about what you're going to say, then say it! Nothing to it but to do it. :)