Get a good quality cold sake. There are 3 main grades so if I were starting out I'd get the middle one, Junmai Ginjo, and go from there. Think of sake like you would white wine so they'll run the gamut of dry, fruity, sweet, sour, etc. Lotta times the bottle will have a short description of the flavor profile, if not, ask the wait help (...or sushi chef if you're sitting at the bar at a sushi place...) and they can recommend something close to your tastes. Don't always be fooled by the price tag, sake, like wine and cigars, is often times a personal choice so what tastes good to me, may not taste good to you. Trying different types and grades will help you determine what you like and with what foods. I rarely eat meat when I drink sake, I have mostly sashimi and sushi topped with raw seafood (...toro, cooked octopus, ebi, and scallops are good...). My favorite pairing is hamachi (...yellowtail...) with sake. I don't "waste" hamachi on sushi, I eat it as sashimi so I can savor the softness and the way it melts in my mouth.
But, like I said, a lot of it is personal tastes so have fun trying different ones.