Assassin's Creed

By equipping the throwing knives you can use a dagger in melee combat. The dagger is good because your counterattack is generally a one hit kill. I didn't realize this until I beat the game, and just used the sword for all close range combat. It makes fighting multiple enemies so much easier.

Don't waste your time 'spergin out on trying to do everything. Just do the minimum number of informer missions, explore the interesting parts of the city and climb a few buildings then do the assassination mission. Its far too easy to bore yourself with a "100% completionist" attitude.

The intelligence that you collect isn't just a prerequisite to doing the assassination. If you go into the options menu you can actually read the letters or look at the maps you collect. Which can be used to assist you in assassinations.

Don't lie to yourself that you're still having fun if you really aren't. Don't expect the game to change and get better, because it won't. What you start out doing is the same as what you're doing at the end of the game.

Something about throwing knives that the game is really bad at mentioning, if you run out you can pickpocket more from those big thug guys who wander around towns.

You can use the hidden blade in normal combat as well. If you do a counter strike against an enemy with this equipped, it's a one hit kill on everyone - even boss characters.

Play in increments of about an hour a time, you're less likely to find it tedious.

Explore the lab in the in between bits, there's a lot of story that is quite interesting.

A lot of the assassinations seem to be scripted so don't get frustrated if a target keeps spotting you etc, it's probably meant to be like that, main example being the trap in the church, which led to an awesome street wide chase.

Explore the lab. Check every computer you can for new emails every day. It'll give some mildly interesting backstory.

On a day where Vidic starts the morning by the window with his back to you, you can pickpocket him.

Doing every investigation in a city, saving all citizens and finding all view points will increase your life bar. Do it, if it doesn't bore you.

The window on the counterattack with the short blade is a lot bigger than on the longsword and can easily make it your go-to weapon.

The window on the hidden blade counterattack is small, but if you can pull it off, you will feel totally awesome every time. It also instant-kills every enemy.

You can view the maps and letters you obtain in your menu, as well as Altair's comments on objectives he's completed. This extends to the end of the game.

You don't have to do everything to get the full life bar, so do what you enjoy. Viewpoints are pretty much required so you can get waypoints to actions, but don't feel like you have to do it all.

After you get the short blade (after you first real Assassination), you can use it exclusively for group combat. For rescues, I'd run in and shank somebody (they aggro if you target them, so hope you don't hit the innocent) then whip out the short blade for the combat

Go ahead and shank the beggar woman if no guard is near, you'll resync and feel a lot better.

Sometimes it's easier to fight than to run. If you kill all the alerted guards you'll go back to incognito (assuming you can get away from the pile of bodies before the other guards show up.

Before you get to skip the travel area between cities, just have your horse hall ass. You'll actually loose aggro after you've ditched the guards, and when you get into the city zone, you'll reset anyway.

Don't worry about flags & Templar. They're just for OCD people, there's no reward for collecting them.

When rooftop running, you can jump->shank the archers before they realize what's happening. Apparently the guards are put on roof watch. Even if you see another in the distance, he'll probably ignore the fact that you just killed his buddy and tell you "you're not supposed to be up here" as you barrel toward him with murder in your eyes.

The rules go out the window on a real "hit". I think I only had one or two kills that didn't hit the fan early. Don't feel bad when you're cover is blown and you're barreling through streets after a guy.

Pace yourself. If you try to rush through the main plot you'll probably get burnt out pretty quickly, so try to tackle a few side-missions, find the high points, and just explore or whatever you find fun. Oh, and you steal throwing knifes from the bulky-looking builder guys walking around the streets. I'm not sure if it tells you that straight away, but knifes are extremely useful (instant kill on anyone who hasn't seen you) so you'll want to keep up a stock.

Achievements

If you're an achievement hunter, you'll want to pay attention to a couple of things right from the offset. The first is to make sure you talk to Lucy at every opportunity, you get an achievement for having every possible conversation with her (mostly just useless chit-chat as far as the plot's concerned, though). You'll know when she's done talking because she'll say something like "I've got work to do." The second is seeing 85% of all memory glitches, which I didn't do at all so I'll just pull a description from another site: When cut scenes occur dealing with who you need to assassinate, you will notice a little "glitch" type thing go across the whole screen, at this time push any button and it will change the point of view on the cutscene. This will occur for every assassination so pay attention to the cutscenes and you will get this before game end. You can miss a few but to be safe always pay attention and look out for the glitch as several occur during each scene.

They're only worth 20 points each, so probably nothing to stress about, but if you're a huge completionist then you'll want to get them on your first time through because going through again just for those would be a pain. The only other not-so-obvious one is a 50 point achievement for sitting through the credits, which sounds simple enough but the credits roll for what seems like a half hour, so you might want to make a sandwich or something.