Completion bonuses
Finish the game. When the Memory Blocks are played again in Story mode you can kill anyone with no penalties. Also you will be able to use Eagle Vision at any time regardless of Synchronization levels inside of the Animus.

Hints & Tips

Beating William of Montferrat in Acre
After the guards leave William, drop down from the castle and kill William. Afterward, "de-target" or deselect, and run up into the castle buildings and battlement to get away. This is the fastest way of finishing the mission.

Beating Templars
Equip the hidden blade. Then wait for him to attack you so that you can counter attack, killing him in one blow. This is better than the sword fight. When your sword fighting if you counter, you will only knock him down and not kill the Templar.

Beating Al Mualim
When you first engage in combat mode against him lock on to him. Equip the hidden blade before you attack. Wait for a counter and you will beat him with the first blow you hit him. Note: This is after you fight Al Mualim when he makes six duplicates of himself. 

Beating the Master
When your fighting the Master he will take away your ability to use radar and make it hard to see. This will allow him to hit you once and kill you. Lock on to him and use a throwing knife. This will take away his power to blind you and make him easier to kill.

The first part is easy. Take your sword out, as you will be fighting all your earlier assassination targets. They are easy to kill. Only one counter is needed to kill each of them. For the second part, as soon as Al Mualim releases you, use your Eagle Vision. The real Al Mualim is the one in yellow. Focus your attacks on him. In the third part, Al Mualim takes away your synchronization bar and radar, allowing him to kill you in a single hit. Take out your throwing knives. Look for the Piece of Eden in his hand. When you see him, throw a knife at him. Thenm counterattack/grab break him. Keep doing this until he says, "Damn you Altair!" Finish him with your hidden blade, or keep attacking him with your sword until he is dead.

When Al Mualim is ready for the last part of the battle after his third speech, lock on to him and equip your hidden blade. Move closer to him and when he is ready to attack, counter him to score an instant kill. He will fall to the ground and you can assassinate him without chasing him all over. Only do this if you have mastered the use of your counter attacks.

Escaping from guards
Go to a high roof when your chased. Kill the guards that appear. After a few kills they will either run or give up.

Easier interrogation
After you get the "target" to a safe area to "interrogate" them, punch them first then "grab" them for faster completions. It will take about two grabs to finish them. However, into the last three quarters of the game you may have to grab them up to four times.

Unlocking doors
When you go to bed after Memory Block 2, you will notice your closet door is open. Hit any button to get a piece of paper Desmond notes as a code. The code will unlock your bedroom door which will allow you to be able to go out when you like after you are put to bed, as well as to open the meeting room area. You can also pick up several items to unlock Lucy's password.

Lucy's computer
One item you can pick up after being able to access your bedroom door is Lucy's password. You can then investigate her e-mails, which entail a short secondary story line. After you finish the last Memory Block, go back outside your room. Go to Lucy's computer. In "Deleted Items" is an e-mail which entails her talking to someone about a rescue, then the last reply comes back as:

WondEr Why It is everyone Laughs at you?
i'll Let you guess.
let's just say she's proBably gEtTing it bigger and better from someone else tHat isn't you.
how can you hope to compEte?
REst asSured there are sOme gOod ways.
click the liNk to see!
 

Removing the capital letters out of the message decodes the message as

WE WILL BE THERE SOON

Hidden messages
After you kill Al Muaiam and return to the real world, listen to the conversation about how they are going to kill you. Turn on your Eagle Vision and look at the floor. There are a few mixed up letters on both sides of the Amnius. You should see on the side closest to the main door:

M O R Y M N O E S
E N C E O L C H T
H O N B T L O T C
T D E O S A T O A
P E D S N L S T F
L D D U O O E T E
E A I E I R I N T
H S H K T T K E R
T U A A A N S S A
 

To decode this, start reading at the bottom right hand corner to the top right hand corner, so you will start at "A" and stop at "S". It will spell a real word. Do this for all of the columns and it will read:

ARTEFACTS SENT TO THE SKIES TO CONTROL ALL NATIONS TO MAKE US OBEY A HIDDEN CRUSADE DO NOT HELP THEM
 

Next, do the same thing to the mixed letters on the other side of the Amnius:

A
D R H
O O D T M
W H B I T D O
E U S Y S I N S E
A R O O M R E A Y N R
I S E Y T N I D L M I D E
T W I H W Y I E A U D A Y H T
 

It will spell out:

THEY DRAINED MY SOUL AND MADE IT THEIRS I DRAINED MY BODY TO SHOW YOU WHERE I SAW IT.

Easier fights
Note: Only try this if they are fluent in the Rank 2 skill "Counter" and they have enough synchronization bars. One and a half rows of bars is enough. When your in battle, equip your hidden blade. With this equipped, all of your counters will score an instant kill. You can instantly kill tougher ranked guards. Also, most of the time using the hidden blade in battle will scare the last one or two guards, making them to run away. Since you do not have a weapon that is good enough to block a full sized enemy blade, all incoming attacks will hurt you.

When your in battle, if you see a guard you are fighting physically emote in any way press [Low Profile Assassinate] while you face them to score an instant kill without having to counter.

The best weapon for more than four guards or thugs is the Short Blade.

At times the guards will beat up on you and it would seem as if your timing is off using the counter attack. To have a little breathing room, tap [Action/Use Your Weapon/Attack] twice, then "grab and push" the guard. Ignore the guard you grabbed and pushed, and attack the others using the same method. There are two ways you can finish them. The first is, after you "grabbed and pushed" all of them, use a strong attack. They will fall fast. The second method is to "grab and push" them again. They will not get up.

Maximize efforts for each city
To lower the time you need to finish the game and to lower the difficulty of each major assassination, do the following in order (with the exception of Masyaf).

1. Visit the Assassin's Guild.
2. Scan the city by first climbing all of the view points.
3. Rescue all the citizens from the thugs. You will need the help after a major assassination.
4. Complete all of the informant's missions (to get all the valuable information you can).
5. Pickpocket the shysters in all of the pickpocket missions (for information to the Guild).
6. When all of these are completed, go back to the Assassin's Guild and get ready for the major assassination mission.