很多卡收 1%~3%,但不少"旅行卡"是 0%。带一张免境外费的卡出门,能省不少。Many cards charge 1%–3%; plenty of travel cards are 0%. Bring a no-fee card.
银联对人民币通常免货币转换费,有银联标识优先走;同时提前告知发卡行出行,避免被风控冻结。UnionPay usually waives the CNY conversion fee; also notify your issuer so travel spend isn't blocked by fraud controls.
出发前查一下目的地货币的中间价(搜"X to Y"即可)。刷卡时对一下,一眼就知道有没有被 DCC 加价。Look up the destination currency's mid-market rate (search "X to Y"). Compare it while paying to instantly catch DCC markups.
相关:境外刷卡最划算攻略 · 境外 ATM 取现的坑。Related: cheapest way to spend abroad · ATM traps abroad.