Keep reminding yourselves that this is about the children's welfare and feelings and that if there are constant disagreements between the parents, this will upset the children.
Have a relaxed attitude about visiting times and different ideas about parenting - so many people take up a position to hit out at the other parent rather than because it is really necessary. The children are not pawns, to be used to inflict pain on the other parent - they are little people whose needs are more important than the pride or manipulation of either parent.
Try not to buy the children's favoritism with bribes or by running down the other parent. The former is bad for the children's character, and the latter simply disturbs the children who may feel guilty because they have divided loyalties.
As a family law solicitor, I have been much saddened by the selfish attitude of parents who put "winning the battle" above their children's happiness and peace of mind. It's hard enough for the children anyway, so try to appreciate what they are going through from their point of view, as well as just seeing your own problems. And remember, however things turned out eventually, you did once love each other. Try and remember the good times.