Don’t be surprised if the first words spoken to you in Miami are in Spanish - it will likely be a theme of your trip. English is obviously a widely spoken and official language, but it’s not uncommon for people to assume you’re a Spanish speaker. English speakers fear not - signs, menus, and everything you might need will be in English. Unless you take a (highly recommended) trip to Calle Ocho (8th Street), also known as Little Havana. Spanish speakers will revel in the various dialects and cultures of Spanish speakers, dominated by Cubans but including populations from various Caribbean countries, Mexico, and Central and South America.
Here's a mini crash course:
Hello! How are you? / ¡Hola! ¿Cómo estás?
Do you speak English? / ¿Hablas (tú) inglés?
I don't speak Spanish. / No hablo español.
Where’s the toilet? / ¿Dónde está el baño?
Good evening. / Buenas noches.