The first mission will begin in Boston. Start off by using fast travel to reach the Frontier and from there head to the town.
You can equally fast move to the shore, where Samuel Adams is waiting for you.
Optional objective: Stay below notoriety level 2.
Follow the man and afterwards help the fighting citizen. Try ending the fight as fast as possible so that you can avoid rising your notoriety level to 2. Otherwise you won't complete the optional objective.
After the fight you will be able to go meet with Adams and will also unlock district challenges. They have been described in a separate part of the guide.
Optional objective: Limit firearm use - 6
Optional objective: Use powder kegs to destroy smuggled cargo - 3.
Optional objective: Completed all the constraints in one playthrough.
Speak with Samuel and head to the shore. There you will receive a mission of destroying smuggled tea. To do that, approach the crates an press the interaction button so that Connor places a bomb which will blow up the cargo. However that way you won't be able to get full synchronization.
To complete the optional objective, you need to destroy the tea by using the gunpowder barrels lying nearby.
Pick them up with the interaction button, place beneath the cargo and shoot with a pistol. If you run out of ammunition, kill a nearby guard and use their rifles. However make sure not to use firearms more than 6 times to complete one of the objectives.
After everything blows up, head to the designated place and kill the tax collectors found there.
Your nest target will be smugglers who you can find walking through Boston. Kill two of them and the mission will end.