This only applies for campaign, haven't tried MP.
Two to four heavy bolter turrets by each entrance to my base. Once I get the heavy weapons teams I put them in front of the turrets, upgrade the turrets to rocket turrets, and the teams to autocannons
Then I bring up a pair of basilisks as soon as possible and put them at each entrance.
Once the defenses are in place I put together an attack force of kasrkin, ogryn, command squad, and three or so guardsmen squads. The ogryn get a psyker, kasrkin a priest, and the guardsmen get commissars. The guard squads also get 3 grenade launchers (or plasma rifles, depending on who I'm fighting). Basilisks may be moved to safer areas outside the base to provide Earthshaker support for the infantry.
This strategy let us wipe the forces of Chaos and the Necrons off of the face of Kronus. Wave after wave of their forces crashed against our defenses, but we held the line. And when it was our turn to go on the offensive, we slayed all that stood in our way. Turrets were flattened before they could do any real damage. Chaos Space Marines and Necron Warriors broke rank and fled. Even the mighty Defilers and Tomb Spyders were no match for our courage and numbers.
Poll