Byz, High, Expert

[Gilrandir]

When I'm up against a faction with a strong naval power I usually try to concentrate my dispersed ships in a few sea zones and make several strong navies. Then I move them up against any stranded enemy's ships. The AI is normally not smart enough to do the same. But your foremost task I see in securing your maritime provinces from the Sicilian landing. So if I were you I would withdraw all my ships to Eastern Mediterranean and evict all enemy's ships from out of there. Once your maritime provinces are safe you can think offensive at sea.