I am experimenting with uncommon openings, so my first move as white would be 1. b4 with a quasi-fianchetto the following move. Then, I develop my pieces accordingly.
As black, I play the common 1. ...e5 in response to the King's pawn and the English opening (to which I occasionally respond with 1. ... c5).
If I encouter an opening I don't know, I look it up, then reply accordingly by gut instinct and book.
As black, I play mostly the black side of Anti-Sicilian BS. Once in a blue moon, I get an open sicilian, and then I play the Dragon. Why? Because it's fun and it sounds cool.
Against d4, I play the Tarrasch, because it was the only d4 defense I ever understood worth a crap. I'll be damned if I'm going to play some defense that has me moving my knight back to its starting square halfway through the game as a point of theory.
With white, I play e4.
I play the Italian in the classical style with early d4's against everything. It ain't going to win me any trophies, but it keeps me from having to reinvent the wheel every time out.
Against the Sicilian, I play the open, and I do my damndest to play the mainlines. This is my tip of the hat to my fellow Sicilian players, who didn't go through all the trouble of learning to play the blasted thing just so they could face 2.Bc4 or some other bull shit.
Against the French, I play the advance. Why? Because that way, I get to play in a way at least some decent players wouldn't scoff at, but without having to learn what to do against 43 different black schemes. I occasionally play 2.f4, just because I think it freaks the Frenchies out, and it ends up playing a lot like an advance anyway. I sometimes think I might take up the King's Indian Attack, but then I think hypermodernism can bite my ass.
Against the Caro Kann I play the Panov, because it's just enough like the Tarrasch that I feel like I can wing it without getting killed by the fancy pants booked up college kids at the coffee house.
Against Alekhine's I play Nc3 and hope they don't know what they're doing either. Pretentious dainties. If I ever get around to it, I'm going to learn the 4-pawns attack, because cramming pawns down the throats of people who want to prance around without doing anything appeals to me.
Against the Scandinavian I play the Blackmar because screw the Scandinavian. If I wanted to play against your glorified Caro Kann I wouldn't play the Panov, now would I? Maybe you don't play the Scandinavian that way, but I can't be sure, now can I? You don't tell me what to do. I'M the one playing white.
Against the fianchetto crap I play Be3-Qd2-shove-the-h-pawn stuff. It works.
What you got?