4) Start the story, but break away early and do the Den stuff You can play the campaign of Assassin's Creed: Revelations straight through without touching the heaps of side-quests tossed into the streets of the game's beautiful, busy main territory of 16th-century Constantinople. You can't even start the side quests until the game's linear action-movie-style first chapter ends. Let the second one begin but then do like I did and break out on your own by the middle of chapter three. The reason I suggest this is because the game's city is essentially one grand chemistry set.
Doing the right sidequests will make the game a pleasure... and makes it the most fun. The main thing you want to do is keep the Templars from over-running the city. If they do, you'll have a harder time getting through the city and the missions baked within the city without constant hassle from the authorities.
Keeping those Templars at bay is complex. Here's what you do: go to the six Templar Dens in the main, southern landmass of Constantinople. Hunt down the captains of those dens and light their signal towers. That will cause handy ziplines to be built in the region around the Den but, more importantly, will let you start recruiting assassins to your brotherhood. Those recruits can be summoned at any time in the game to help you in a fight, but what you want to do is to also dispatch them into the game's Mediterranean Defense strategy game, where you can assign them missions and level them up. Getting them to level 10 lets you go on a fun mission with each of them in Constantinople. It also lets you assign them to a Den and rank them up to level 15, at which time you get to go on another mission with them (these missions are good!) and, more importantly, locks the Den off from Templar incursion.
All of this is useful because, until the Den is locked off, the Templars will try to reclaim it. They'll attack if and when you commit enough suspicious or aggressive actions to fill an awareness meter atop the screen. You don't want to fill that meter up because it will put your Dens in jeopardy and because the tower defense mini-game you have to play to protect a Den isn't very fun. Get your folks to level 15 and so many of your problems are solved!