Ideas for OP fire when playing solitaire?

[saracv3]

I usually take at the first opportunity. I understand the dilemma. Does one take it when the enemy is advancing at three hexes, two, or one? You know in your mind what’s going to happen. But I’ll usually take it at the time that might be most “realistic.” In other
words, if the enemy is advancing to attack, take it at two or one hexes. If the enemy is just passing by or going away, take it at the first opportunity.

I just had a situation tonight where a stack of Germans were leaving a village because their position had become untenable. They advanced one hex and the Maoris took opportunity Fire- no effect happened- lily for the Germans. They could only go one hex. Most of the stack was dispersed.