Don't be tempted to waste money on Edward or your pointless hideout upgrades – you'll want to spend the vast majority of your loot on your ship, as the toughest missions in the game are all naval based. You might be tempted to avoid encounters and sail around them, but it's important to engage smaller ships at the very least, so you can earn more materials to upgrade yours (don't forget to sell your sugar and rum, as they have no point other than to barter for cash). Along the way you'll find crew members to save and materials to grab in the open ocean, as well as ships to pillage, which allows you to upgrade your own vessel. When you first acquire your ship (The Jackdaw), sail everywhere – no exceptions. Having said that, try not to rely on fast travel too much – you will regret it later in the game. To fast travel to a specific area on the world map, zoom all the way in rather than looking at it from a macro level and you can pick a specific quadrant of a town.
When you enter each new area, try to make sure you climb one viewpoint and synchronize it – in Black Flag, each synchronization spot is a fast travel spot, so if you need to get somewhere fast, it helps to have covered all your bases. Eventually, you'll want to actually play the game.