Half of the time you practice your target language and half of the time you practice your native language for them. Its 50/50.

When you are with your friends, do you keep track of the times you say nice things to each other, or sympathize when they need a shoulder to cry on, or when they help you? When there is a need your friends try to help and you do the same, and when something wonderful happens you share that with your friends too perhaps. Bad friends abuse their position, manipulate, take and never give, do not value their friendship and people like this should be avoided I believe. I believe that if you are a professional teacher then you have an obligation to provide a service, my teachers at school were such as that. If you are a tutor or a language partner then your role is as a resource and you will hopefully be pleasant, helpful and friendly. There are a number of ways to sort this dilemma about who teachers who and when and the person you should be talking to is the person concerned. Don't think that it takes a special person, rather it takes simply 2 people communicating and discussing about options and respecting each other as individuals.

well... I have two possibles solutions for you. One: If you want to learn a language and you interact with someone who wants learn yours, so you can to plan a class to you practice that idioma you need, and in other class this person can practice your idioma native. To this way both of them learn and teach. And like an extra, both can have several classes. :D tow: Another solution for you, could be that first take your time to learn this language, and then you can teach. I hope had help you.

If you are native or fluence in some language you can teach