Bring Plenty of Cash

There’s basically no place in Cuba that will accept a credit/debit card as form of payment. Everything’s cash-only, even major hotels and tourist attractions.
There are some ATM machines in the country where you could get cash, but American cards won’t work there (European and Canadian cards will though).
In the end, remember: Cuba can be a great experience as long as you’re willing to adjust and go with the flow.