Keeping the German fleet near friendly land. Initially, stick to Denmark and the Baltic, using a maritime bomber and MDM to punish any RN ships that stray too close. Don't reveal the maritime bomber till they get sloppy with their CV's or BB's. At the start of Barbarossa, send a maritime bomber, fighter, and MDM to Norway. Have as sub wolfpack with 1-2 CA/CC's operating with them. This generally will draw a response from the Royal Navy. Once the RN attacks your pack, then unleash your land based air to hit a known ship, draw out any CV air, and reveal other ships, then hit and run with your subs and CA's.
At the start of the game, you can also send your at sea ships south in an extended move. Concentrate on reducing the South African convoy port. Set a CA/CC in the port zone and flank it on both sides with subs in "silent" mode, so the Allied player doesn't detect them when they send ships racing to remove your CA. A pack of 1-2 CA's with 2-3 subs can do some damage.