Find all 32 Secrets Of London (music boxes). Then, take them to Reuge's Vault.
Interact with all levers in the vault to unlock the Aegis outfit, which is the
best outfit in the game. Note: It can only be worn by Evie.
All Royal Letter locations:
Search the indicated locations to find all 12 Royal Correspondence Letters and
get the "A Life In Letters" achievement. The merchants do not sell maps for this
type of collectible. Fortunately, they are all fairly close together in Buckingham, Westminster. Use eagle vision when near their location to see them on the map. If you buy the skill upgrade that increases eagle vision range, it will be easier to find collectibles. You can buy treasure maps for chests, beer brands, historical posters, and pressed flowers from merchants (e.g. from the black market merchant in your train). All Royal Letters are saved automatically when collecting them. You can view how many you have found on the map.
Easy "Look Out Below" achievement:
A great place to kill three enemies with a single stack of hanging barrels is at the start of Sequence 4: Memory 2. There is one enemy standing under hanging barrels and two others will come to talk to him. Shoot the barrels with your pistol when they are standing underneath to instantly kill them and get the "Look Out Below" achievement. Note: You can replay this mission any time by going to the main menu and selecting "Progression Log", "Progress Tracker" to replay it.
Alternate costume colors:
Successfully complete the indicated task to unlock the corresponding color:
Beige : Purchase for £1,000.
Beige and Blue : Purchase for £1,000.
Black : Collect 20 Pressed Flowers.
Crimson : Collect 30 Pressed Flowers.
Forest Green : Purchase for £1,000.
Fuchsia : Collect 10 Pressed Flowers.
Gold : Purchase for £500.
Green : Inside a chest in Spitalfield Market.
Midnight Blue : Collect 15 Pressed Flowers.
Steel Gray : Collect 25 Pressed Flowers.
Taupe : Purchase for £1,000.
Teal : Uplay reward.
Ubisoft Blue : Uplay reward.
Violet : Collect 5 Pressed Flowers.
Wine : Successfully complete the Karl Marx Memories.
Spend the indicated number of skill points in Jacob's and Evie's skill trees
to increase their level as listed below. As they level up, new equipment and
other tools will become available.
Level 1 to Level 2: 4 skill points.
Level 2 to Level 3: 4 skill points.
Level 3 to Level 4: 8 skill points.
Level 4 to Level 5: 10 skill points.
Level 5 to Level 6: 10 skill points.
Level 6 to Level 7: 10 skill points.
Level 7 to Level 8: 15 skill points.
Level 8 to Level 9: 15 skill points.
Level 9 to Level 10: 18 skill points.