I find, early in the game, that if you get two planes incoming on radar then it is Zero's. Those are tough and it's better to dive. A lone one is usually a Betty. If I'm in a rush, I dive to 40'/45' until it's past. Otherwise I take control of the AAA gun and give it hell. If I don't destroy it, I at least send it off in flames!
If you get a good gunner crewman though, it's fun to watch him kill it from the bridge.