I love to solo board. My favorite way to sail alone is to jump on my sloop and attack Kingfishers. I weave back and forth to take them out with my broadsides while behind them (you never really get attacked that way. frigs and gals are too slow to turn, but sometimes a sloop can). Then it's just attune, poke, poke, poke, die Navy swine!
As for crews, well, I enjoy plundering with my guild. My cannon level has skyrocketed because of it. We don't have the shoot "anything that moves" mentality, more like the "shoot anything that's above level 30" mentality.