[Aiken]

It's a well known strategy, but I'll mention it nevertheless:
If you want to achive maximum efficiency in ground combat, it's worth to design 3 types of troops: Defender, Offender and Leader.
Defender's design include small shields (or armor) only. Offenders are armed with you favorite weapon (ground cannons or small shield depleters) and nothing else. Leader is equiped with shields plus small combat sensor and small ecm components.
Produce them in 3:6:1 proportions (rough numbers). Now, then filling your troop transport, place Defenders first, then Offenders and Last Leaders. Being dropped to a planet, Defender will play a meat shield role, Offenders will stay behind Defenders unharmed and wipe out militia (or hostile troops) and Leaders will provide attack and defense bonus to the whole stack of troops.