MIke,
Tactics will generally depend on what your specific mission is. Its hard to give one good comphrensive answer.
Geoff is heading you in the right direction, infantry needs to coordinate with afvs.ie: a half squad can help protect an OT afv, lets say a marder from snipers by being in the same hex,possibly absorbing a 1 SAN,infantry can also keep enemy infantry at distance perhaps denying an enemy LATW a shot at your afv.
Also, you can possibly flush an enemy ATG with infantry etc.Again, it really depends on the specifics of the scenario and what the enemy has to oppose you.Might make for a neat talk over lunch at next game day, what do you think? ev