In short: spirits, wine, the glassware you might need, and, of course, your cocktail-making essentials. Yep, that means the cocktail shaker, too. That said, it's totally your call. Some people keep only their liquors on it, while others kit it out like a fully-fledged bar — ice buckets, mixers, the lot! All I'll say is that fizzy wines and soft drinks are probably best kept in your refrigerator, especially if yours is a smaller cart.