The first thing you should do is get one of the supermods. Which one doesn't matter, they're all good. The stock game has some bugs that will come to bite you sooner or later.
As for orders, you've already gotten some good advice. I'm just the opposite. I stay in my assigned grid for at least a week, and have my own complex system for changing locations (or not). I've had more than one empty patrol, returning home with no sinkings at all. On the other hand I've been playing sub sims for thirty years now, and at some point just sinking things gets boring in itself.
But that's just me.
