Easy Battles at Sea:
This works best with eiher grape shot or chain shot.
When you're fighting other ships, get in front of them and make them chase you. Turn, unload on them, and straighten up again.
Just keep doing this technique until you want to board or their they surrender.
Get Specialists Easily:
Attack and board a Smuggler's Vessel. More often than not, a specialist of some kind will be acquired.