There are quite a number of things one can learn from the Minibattle that can also be applied to any Warhammer game.
I think something to consider if we ever do something of this level again is kind of limit the number of each type of army to each side.
That would help even things up quite a bit.
If you are facing a gunline in a Singles game, and you're going first, what do you do? Think on it, because the answers might save your hide.
Seize Ground/Objectives take the Second Deployment always.
To be fair, you were staring down a gunline, but generally, yes. Objectives = second. After all, you should be deploying to provide maximum protection. If that doesn't work, either the board or your list is faulty.
Dont Depend on Mech lists so much.
Rock, paper, scissors. This is the argument for balanced lists. The counter-argument is to take your chances you won't meet your bane, and if you do, at least to have a plan for it.
Pay attention to everything on the board as a whole.
QFT. Team Black also communicated better than Red.
Placement. Not just deployment but how guys deploy out of a vehicle whether it be wrecked or not. If a guy is close enough to assault one guy he can assault the whole squad. I know we had lost some pretty decent guns because we had to get rid of those guys to prevent assaulting.
That comes with time and practice. But congratulations, that's next level thinking!