I am not sure if I am having a successful one but here goes.
There is basically no secret for that. You need to be honest to one another. The more secrets you keep from your partner, the more chance there will be an issue popping up in the future.
Communicate with one another and always try to give and take. Understanding each other is vital as without understanding, there is probably no relationship.
At times, there are things not meant to be discussed to avoid unwanted understanding. Some do not agree with me but for me, some matters are just not meant to be discussed along.
Besides that, always remember not to go straight into serious discussion when talking. Always be patience and try to talk things out when something happen. Also, remember that one side have to be more patience.
Hope this answers your question.