It depends. I've only played DoW, but in Soulstorm, my tactics change with the challenge presented.
Take and Hold
I make a basic base with resource generation, then a bunch of basic units, send them out to capture some points with the leader unit, stick some turrets up, and move on to the next one.
Annihilation
If I know where the enemy base is and I have a strong leader (orks and Chaos particularly), I'll just send in the leader and say kill everything that moves. For the bigger challenges, I love amassing a huge force that cannot be denied and then steamrolling everything in my way.
Take and Hold
I make a basic base with resource generation, then a bunch of basic units, send them out to capture some points with the leader unit, stick some turrets up, and move on to the next one.
Annihilation
If I know where the enemy base is and I have a strong leader (orks and Chaos particularly), I'll just send in the leader and say kill everything that moves. For the bigger challenges, I love amassing a huge force that cannot be denied and then steamrolling everything in my way.