I'm still a rookie, but plotting ones opening gambit has already become a fun passtime. I only play Gowen so far, so let me speak from what limited experience I have.
Thanks to a random card pickup, I find myself likeing to open with 'Highland-Born Warrior' in the first, or second, turn, making sure I have the 5 Gowen needed to turn him from 'Okay' into a pretty solid tank. I've noticed that neither Kurima, nor Combat Monk have the HP to really last in One-on-one fights, so the sturdy, but fairly quick HBW is a happy compromise to hold the line for the first turn or two before I can call on my faster units. I also prefer to put Kurina in the second row... who cares if she can't fight, as long as that Attack bonus keeps comeing? She hits, pun not intended, like a girl anyway.
HBW on turn one, with Rougeerst chiming in during turn two has similarly beneficial results if you, like me at the moment, only have one of the spear-toting butt-kickers to call upon.
Turn three is about gaining the feild and, if applicable, letting your first Soul Card unleash hell. If you already have HBW and Monk/Kurina in the first row, toss a Salamander or Lightning Archer farther back to spread your forces while giving you enough monsters to meet your enemies inevitible charge. Since I do not have any Panther Soul cards, I have to get my Gowen level to 9 before unleashing Brave Warrior... of course, it also makes your Flame Arrow and Fire Tornado spells SO STRONG. Why shortcut?