Many businesses default to using disposable goods. They routinely shell out paper napkins, plastic forks, straws. Coffee cups (and lids and sleeves and stirrers and sugar packets) are generally single-use items. Going out to eat or visiting a favorite neighborhood spot is such an enjoyable experience, but the waste many establishments create is worrisome.
Instead of accepting the single-use serving pieces that come your way, my tip is to just ask. Just ask your server or barista with a smile and a thank you if they'd be able to serve your food and drink using reusable dishes. Even if they usually use paper goods, I find that most businesses do keep glasses and other servingware around. I'm almost never turned down, and I love enjoying my meal more sustainably.
The above picture shows a tasty smoothie from Anodyne Coffee Roasters in Milwaukee, who graciously complied with my request to use a glass instead of a paper cup. I savored it sitting at the counter, chatting with the barista dressed like Kramer from Seinfeld (it was Halloween, after all).