On Attacking

Attacking has been the blight of all matches. Shows how aggressive you are, how taking the hits are better then dealing them, and how creative you can be from taking an early disadvantage and turn it into an uncontested strike that can be to quick to react to.

Example of attacking/rushing:

Spoiler Alert, click show to read: 

Advantages

Overwhelming
As the attacking force; You can choose where to begin an attack.
I personally like to begin an attack on a flank or position of the field that I have the strongest concentration of my army.

If your defending against attackers:
Counter all attacks, but also don't forget as the defender to take advantage of the situation. So make counter attacks to do extra damage and when you feel you can't do more, you should return to your formal position and reorganize.

High Damage at Short Range (Rush forward, don't waste time taking easy shots; Don't waste your troops!!!.)
If you're the one attacking:
You can play defensive as an attacker, as you can be aggressive as a defender.

Aggressive Defense
Attackers most of the time don't commit their full forces. You can trick your defending opponent or fellow aggressive opponent into repositioning a portion of his strength to further weaken a flank for a future attack.

I normally don't commit all my troops into an attack; That way your defending opponent would react in such a defensive way that they would weaken their center or opposite flank for the purpose of reinforcing or repelling attacks on another.

Consequently, in their intention to strengthen or reinforce a weak flank, they've actually weakened another. So that is why battle formations should be kept balanced on each side.

Defensive Attacking (Counter Attacking)
As the defender, you will be given a few advantages that you should use to further gain a early lead against an attacker.

Spoiler Alert, click show to read: 

First Shots
Just be patient and wait for the attacker to do what he does best and he will present some easy targets.
Fresh Troops
Since you are defending, you will be given the advantage of having fresh troops to counter most likely tired enemy units and since counter was said, that's another topic to defending.

You are given the opportunity to Counter Attack an aggressive opponent with fresh troops that you didn't run around. If your opponent was unsuccessful in breaking your flank, you can counter attack his retreating or weakened flank.

Doing this will often end up successful if you react quick enough, and it can end up unsuccessful if you split up your united force to much to lower their overall superior advantage as one uniting front.

Countering
As the defender, you can still be aggressive and it's highly recommended.

Spoiler Alert, click show to read: 

Hannibal knew how to gain a victory, but he didn't know how to use it.
Once you beat an attack, you should finish it off.

Make the damage count, don't let such a small victory be lost because you didn't take advantage of the weakened troops that will only regain their morale and get fresh after waiting for a while.

Artillery


Bringing artillery as the attacker makes you a defensive attacker, but you are still an attacker if you use your artillery to weaken a position of your opponent's side of the field for an attack option.

Spoiler Alert, click show to read: 

Uploading a video of this example soon...

Attackers Vs. Morale

An attacker must only attack morale ONLY.
As an attacker, attack where you are strong. Attack the weak line Infantry with your guard units, attack the saber wielding cavalry with your lancers, attack the enemy general, shoot the flanks, surround, and use cavalry/Infantry combined attacks.

As the attacker, do and complete the following before doing the next objective: Attack the weak, overcome or overwhelm the strong, divide your enemy or break through them, shoot the flanks, shoot from the front with Infantry but only do so with cavalry support from behind, never bring forth the cavalry without Infantry support, and TAKE OUT THEIR DAMN GENERAL!!!

Disadvantages

Friendly Fire

If you're the one attacking:

Don't place your troops in front of the other. Never waste your overwhelming numbers for nothing.

If you're up against attackers:

Maneuver around so your opponent can't concentrate a portion of the force he sent. Splitting up your army will lower your opponent's firepower but will also lower yours, but as long as you get the first shots, splitting your opponent's force should benefit your army more then theirs.

If you're up against defensive attackers:

BRING THE FIGHT TO THEM

You can deceive an opponent into thinking your attacking by doing hit and run attacks on units with your skirmishers. Most defensive players bring four 100 Range Light Infantry units (Prussian Fusiliers, Light Foot, Chasseurs, etc..) and one 125 Range Rifle for the purpose of shooting your army from a distance to force you up into the range of their light Infantry.

So if your defending, move up to give your army some space and lure your opponent up.

Attacking on Terrain maps

Terrain
As an attacker myself, I call these obstacles, more then calling it terrain. I normally enjoy matches to it's fullest on a flat map, but you should be a All-Round-Based-Attacker on any map or situation.

Attacking on terrain maps are with some higher difficultly, but can just as easily turn in your favor. Just because you declare your the attacker, doesn't mean you have to attack immediately.

On Terrain maps, I observe my defensive opponent for a while.

"Never interrupt your enemy when he is making a mistake" - Napoleon Bonaparte

Every player will have a weakness or flaw in their build, formation, or the simple under-usage of a particular unit that he should be moving around. (General's Staff for example)

I wait, then I plan and if it fails, I plan again.

Micro
Being the attacker requires you to overwhelm efficiently. So micromanaging your units to their full capabilities will help in this task.

I practiced all the time to achieve fast micro and I use custom hotkeys to speed up this process.

Example of Micro:

Spoiler Alert, click show to read: 

Just practice whenever you can, and I have a simple way of forcing myself to move about quickly.

Micro Tip: Watch an area and look everywhere quickly and count to 3 seconds. Then move somewhere else.

Always check your mini map. Never stare at a fight, check it 3-6 seconds later.

I still need to cover the topics of flanking and adapting to any situation that presents itself while attacking, but Im going to play a few matches, watch some football, and drink some beer before I finish this

Ask any question and I'll answer it about attacking. If you want an example of it, then I'll show a video I have uploaded already. If it's not good enough, then I'll make another based entirely on that topic.

well done + rep

nice guide mate...

Good guide, but you should be a bit more specific sometimes.

Originally Posted by Point_Man

As the attacking force; You can choose where to begin an attack.
I personally like to begin an attack on a flank or position of the field that I have the strongest concentration of my army.

What I do is beginning the attack at the position where the defender is weakest, if necessary move your strong troops there.
In addition, anticipate what the best defensive move against your attack is and maneuver surrounding troops to be able to take advantage of it should it occur.

If you want an example of it, then I'll show a video I have uploaded already. If it's not good enough, then I'll make another based entirely on that topic.

The sample videos are a good idea
I think it would be better if you provide short clips demonstrating exactly the situation you describe instead of full-blown commentated battles.

i like this post, especially micro technique.