The three tangible ways I have identified to personally improve my relationships with Christians from other traditions are:
-Respectfully engage in dialogue and conversation. Not with the aim to convince but to understand the conversation partner. A difficulty with this is that theological debates often tend to revolve into fierce arguments, where love is lacking. In practice, it is challenging to act in an ecumenical spirit when others firmly believe you are wrong and sometimes even want you to change you opinions.
-Visit an Orthodox service. I have attended quite a few Catholic services as a Protestant but have not yet attended a full Orthodox service yet.
-Present a “mere Christian” position to the outside world, leaving doctrinal debates within the confines of internal discussion. If someone is interested, you can of course engage on the different strands of Christianity. But in principle, I think it is good to show non-believers what the faith is essentially about: the acceptance of Jesus Christ as our Saviour.