Some of the best tactical advice I can think is never underestimate the power of denial. The ability to deny your opponent any advantage you can will turn the tide more times than not. Deny them that first round of assault extras for example can save you squad members, even how you go about assaulting can deny them some much needed attacks. What ever strength an army has, there is some way to deny it. Find that and use it to your advantage. But remember tactical denial can go both ways.