@wholesalefail Best advice that I can give is always keep an eye on the horizon. Ships rarely 'come from nowhere'. You can spot ships from a fairly decent distance due to its silhouette.
From the silhouette, you can usually tell what size ship it is. If it is a ship that is larger than own, you might consider flight, in which case knowing different ship speeds in different scenarios is useful. (e.g. sloops heading into the wind can be a nightmare to catch, galleons with full wind will catch anything eventually).
Or, if you are feeling the opposite, you could choose fight and 'get the first hit in'. In which case, the manoeuvrability and/or size can work to your advantage. Galleons are big and have more cannon and crew than other ships but are slower to turn and get up to speed, whereas sloops/brigs are faster turning and can navigate shallower waters but have smaller crews and fewer cannons.
If you are getting jumped at Outposts whilst turning loot in, then keep an eye out for a mermaid in the water... do a complete circuit if needs be to be sure, or send someone over (if you have a person spare) to have a quick scout. If it looks clear, go ahead with your loot...but always be wary. If you are being chased and want to cash in some loot, try dropping someone off (or yourself) with loot as you pass the outpost and leave your ship sailing onward.
None of the above is guaranteed to work and I'll be the first to admit I am not the best Pirate when it comes to fighting others (pretty much anyone that has sailed with me can attest to that 😁 ) but I am pretty good at avoiding others and still cashing my loot.
Long story short, always keep an eye on the horizon, use your specific ship's advantages to your own and if all else fails remember, "It is not about the Gold, It is about the Glory"