As a Central Powers fan. Amazing, congrats!!
1. Not enough troops for the whole thing? Then for the symbolic value, take Scapa Flow.
2. May you disembark in Ireland? Is the game designed so that it has any effect in a possible rising of the Irish Patriots?
3. The most important thing, the blockade of Britain. This was the main reason for losing the war, so the contrary should also be true.
4. Finish off the Mediterranean Fleet, Suez?