This is especially ment for those who never played MTW (properly). It also explains the basic idea behind all of the mod's unit types, and to point out some differences over RTW gameplay.

1) Army Setup
For those who played MTW: an army that worked in MTW should do fine in ChivTW. That means valor upgrades are very important, especially for infantry. If you want your infantry to hold their own they should atleast be v2, anything lower and they may rout as soon as things look bad. Cavalry dont necessarily need extra valor unless you expect them to fight head-on against upgraded infantry or cavalry.
Next to your melee units a standard army needs 6 to 8 archer units for protection against the enemy's archers (especially horse archers). Their only purpose is to protect the more expensive units from archer fire or to force the enemy to attack, so they do not need any upgrades (unless you have some money left).

2) Heavy Cavalry
Cavalry does not beat most infantry cost-effectively. So for them to be worth their price they need to exploit their major advantage: speed. Also remember that the jump animation is removed so it's no good to throw lots of cavalry head-on against a single unit; only the front rank can fight so it's a waste of units and time. Instead send the remaining units around to flank the enemy. The only advantage a massive charge has is morale: the more friends around the better morale is, and the worse the enemy's morale. Sending a sole cavalry unit into a mass of enemy units will most likely result in them routing after taking the first casualties.

3) Infantry
Infantry should form the bulk of your army, as they are the most cost-effective units in hand-to-hand combat. Usualy it is best to combine light and heavy infantry (especialy in next beta): heavy infantry for the brute force and light infantry to quickly fill gaps or preventing the enemy cavalry to flank the heavy infantry. Guard Mode can be usefull for infantry if they are weaker then your opponent's infantry: it'll give them better protection from their shields meaning they die slower. The fact that they hold formation means they will have much less chance to attack so they'll kill a lot slower. But if their sole purpose is to buy time then Guard Mode can be very effective.

4) Archers
Unless you are prepared to rush, archers are a must to keep the enemy's ranged units at bay. Especially when facing horse archers, foot archers are invaluable. Standard archers and crossbowmen have the lowest range. Most other foot archers have a slightly higher range. Basic Archers are only really good as cannon fodder or to damage lightly armoured units, while crossbowmen can still do quite some damage against armoured opponents. Crossbows are also very effective at keeping elite horse archers at bay.

5) Horse Archers
Unlike RTW, standard HA's do NOT have cantabrian circle. Only "elite" ones like steppe/mongol HA's or szekely can perform this ability. This makes standard HA's very fragile against foot archers. And if you are facing crossbowmen even cantabrian circle wont help much (the straight course of the projectiles assures succesfull hits). Therefor HA's are best in combination with foot archers: foot archers to occupy enemy archers, then send the HA's to harras the enemy's flanks and back.

6) Light Cavalry
Light Cav is capable of catching all horse archers, and that's probably their major advantage. Special LC units like Algaraves (lightly armoured knights), Jinetes (AP javelins) and Ghazi Cavalry (AP axes) can give your enemy a really nasty surprise, being fast and deadly. But keep they out of long h2h fights, for that's a waste of their strength: very high mobility.