Del
Bravo for giving this a go and good luck. I have built a few ships and painted even more. Captains were very picky about the appearance of their ships and spent a lot of their own money on paint and gold trim to keep everything in order. As a couple of guys have said the deck would be scrubbed almost white, this was done every day when possible. The masts would show a little of the look of varnished wood and yard arms were frequently painted black. Blocks would all be slightly differing colours of hard wood but not very weathered since they were vital to working the ship. All standing
rigging would be black as it was often covered with tar to stop it from wearing. If you are not sure standing
rigging is everything that does not usually move when the ship is being worked, so shrouds and stays primarily. The other
rigging would be variations of hemp rope again with little weathering since faulty lines would put working the ship at risk.
As Dave said the sails would tend to grey a little with patches and whole panels sometimes showing whiter due to being replaced with newer cloth. The hull would have some salt streaking but not too much. At sea the area around the bows would certainly be soiled since that is where the heads (Toilets) were located and plumbing was limited to a drop in the ocean.
Finally you should decide if the ship is to be presented at sea in regular cruising, after an action with some battle damage or sailing in to port with everything freshly scrubbed.
You didn't say but if the model is made of wood then it will age naturally and you don't need to do much to it, if it is plastic try all the tips you can find online for making simulated wood.
Like I said good luck with this. To finish here is one of my paintings to give you some ideas.
John