If you played Black Flag, then you know exactly what you're in for.
If not, you're going to need a LOT of materials and money. In order to get a lot of money and materials, always loot ships, and send them to Cormac's fleet to do the management mini-game. You can also get a ton of materials from loot convoys, so check out the achievement guide for looting 20 ship convoys to find out an easy method for doing that. Also, you'll need to aquire a lot of blueprints to do some of the upgrades.
Link to blueprints: (YOU DO NOT NEED THE WHEEL OR SAIL BLUEPRINTS, THOSE ARE ONLY FOR DECOR) https://primagames.com/games/assassins-creed-rogue/tips/assa...
Link to loot convoy method: Solution for What's yours is mine In Assassin's Creed Rogue
Ask if you have any questions.