Command & Conquer 3: Tiberium Wars/Ambushing

To set up an ambush, you're going to want to make sure you have a decent base going. Have around two refineries per Tiberium Field with five Harvesters per Tiberium Field. Train a good mixture of units, this includes infantry and vehicles both, and set them up around the outside of an enemies base. Once the opponent sends out his troops to scout/expand/attack, you destroy him. Then move onto his base.