When you join a server solo go up in your crows and take a look around
if you see other ships don't do voyages in the area that they are lurking around. if the server looks crowded join a new one
There are plenty of times I sail around for a couple hours without even seeing another ship you just have to find a server that matches up with your gameplay wants and needs
When people approach you let them know you are friendly and do not wish to fight. This doesn't stop all pirates but it does stop some
Getting good at dig maps will speed things up so you aren't in one place too long. Be picky about your voyage try to do ones that have easier objectives to prevent you from needing to be in one spot for a long time or far away from your ship
On bounty voyages use firebombs often and kegs to speed it up
Riddles go very fast once you memorize the areas and clues it takes time but once you have it down it'll be quick
Sell often you never regret selling often you often regret not selling
If you start getting hunted and don't want to fight run against the wind with sails in front outrun them to an outpost sell what you have lower your emissary if you have one and just find a new server
It's fine for them to be hostile and it's fine for you to be passive and move on if you want. If you aren't into the pvp part just do what you can to get rid of your loot and bounce.
A rowboat is a solo pirates best friend. Be sneaky with it be smart with it and treat it right, it'll get you outta sea pickles
You can't control what others do or how they act but you can master the art of solo play to where it becomes more peaceful more often
This is a pirate game and people are going to act like pirates but if you adapt through consistency and practice you will be able to solo PVE without a whole lot of issues with other pirates. You'll always have a bad run every now and again but you'll have good ones too just embrace the good experiences and throw the bad ones overboard