Some standard tactics.
This is pretty much a standard attack formation in 1 vs 1. This particular tactic worked very welll on TDI and Nick until they started to get good. It will still work very well if performed decently. Especially with archer units.
First you have a row of infantry. Usually a type of spearmen, but the best ones you can afford with decent valour. You don't want these guys to cave in and run. They are meant to engage the enemy and keep them occupied.
Behind the line of infantry you can put some javelin throwers or archers. Javelin throwers work very well against armoured infantry. They can decimate them in a minute. Unfortunately you need to control your javelins. This require micromanagement which can go wrong in the heat of the battle. You can't keep them in skirmish mode because they will run away all the time. You have to rely on your block of infantrymen to protect them. So you turn skirmish mode off. And place them yourself. And click on specific units you want to attack. No point wasting your javelins on some shit unit. Go for the elite units. The disadvantage of javelin troops is of course that they run out of javelins really quickly. Most can throw 3 times or so. If you do it properly though these salvos of death will hurt elite units that cannot be hurt so easily in other ways, such as 1 on 1 combat with other elite units.
A more relaxing solution is to use archers. They don't need to be so close and can hang back a bit. They also can shoot longer since they have more arrows. Disadvantage is of course that the arrow isn't as deadly, especially against heavily armoured troops. Sometimes it is therefore better to target the weak lightly or unarmoured units of the enemy. Moral can cave in if there are lots of dead people in the opposing army. Or you can let all archer units focus on one enemy unit. An elite one. Or the enemy general. It's a bit the coward way though. I did it once in a battle 2 vs 2. TDI my ally was completely butchered. I saw it happening. I finished Sockpuppet path's general off with archer units, crashing his moral. Later in the same battle I did the same with Nick's general.
Now it is time to plug holes. Your infantry spear units have engaged the enemy and are holding them down. You can have some sword or axe infantry units on the sides which are now send forward to attack the enemies flanks, or at least to pin them down.
Remember that you will never win this battle in the center. The center is just for holding down the enemy. In fact you are slowly losing the battle in the center, because if everything went well his best units are there and pinned down. Otherwise you are in trouble.
With the flanks occupied and semi-safe you can send you cavalry behind enemy lines. They flank the battle and make a concentrated attack in the rear of an infantry unit that CAN lose. No point in going for a suicide attack against the general unit or an infantry unit that is standing around in reserve. Your spear man line is the anvil. Your cavalry is the hammer that will hit a unit from the back against the anvil.
9 out of 10 the crushed unit will pack in and run away.
this is the moment you have been waiting for. You can pull the cavalry unit back or route the enemy. Or you let the infantry unit that was holding the line chase it. The idea is that you now have a free unit in the line. You can wheel the infantry around to attack the flank of the neighbouring enemy unit. This enemy unit has already seen its buddies run and the chances are good they will do the same. If you have send the infantry unit to chase the runners you can use the cavalry for another hammering. You have pulled them slightly back and now you send them again.
If you kept your general unit in reserve you can now direct him to the weak spot to help give the final punch. Once a few units start running you have achieved superiority in numbers.
What is left is to finish the enemy off.
Needless to say the adversaries Nick and TDI have been highly trained now to expect a standard attack like this, but with the right units it is still difficult to counter it.
Standard counter techniques are to use your own cavalry to block the flanking of the cavalry of the attacker. Or hold some units in reserve that protect the flanks.