1. Find all of the same Type

When you need to select every Unit of the same Type (such as all of your Spearmen) you can simply hold Ctrl and then left-click on one of those units. It will highlight every Unit of that Type on your screen.

This is very useful for situations such as when you want to move your Spearmen to defend against the flanking Cavalry of your opponent, or when you want to use your own Cavalry to flank the enemy backline.

Another way of selecting every Unit of the same Type is using the "Find all of the Selected Unit" Hotkey (inside the Find Unit Hotkeys section), but beware that this will select every Unit (or Building) of the same type in the match, regardless of where they are, unlike the Ctrl-Click method which only selects the ones on your screen.

2. Easy Drag Military

Enabling this option inside the "Camera and Chat" section of the Options menu will allow you to select only Military Units when dragging a box around them.

This is particularly useful for moving your Military Units around without taking your Villagers off of the resource they were gathering.

If you enable this option, you can hold Alt and then drag around your Units to include Villagers (and other non-Military Units, where applicable) in your selection.

3. Raiding and Defense

Harassing your opponent's economy is pivotal in securing yourself an advantage and winning the match.

Send some of your faster Units to attack the enemy Villagers. Cavalry and faster Infantry Units are great choices for this.

In return, you should have some of your own Units next to your Villagers in order to be prepared to defend against your opponent's raids.