Submarine Beginning Strategy

Escort ships seem to spot me right away and I do not seem to be able to hit them with torpedoes. How can I approach a beginning strategy?

I seem to be able to complete various missions with PT Boats and larger craft, but submarine missions seem alternately boring and frustrating without a hint of how to start a plan.

There are several tips for the sub missions here and there on this forum, there is even some "walk-thru's" too for some of the missions.