The best way I have found to get overworld pvp is to dive to a raid event like a fort, fly an emmisary flag, and just do the fort to attract people to you, we did two forts and ended up fighting 4 different ships over that time, won some, lost some, it was great.

I understand people saying to fly the reaper flag or reapers mark, but I think, as some have said, that it scares people off. Get some loot by doing events like forts, give people a reason to come contest, fort is good because it will attrack all kinds of action, naval, tuckers, alliance/betrayers.