Best advice is to improve your current Spanish skills. The more Spanish you speak the better it will be for you. Cubans are incredibly friendly. They don't live in our world of mass culture media - they don't have endless choices of newspapers, glossy magazines, billboard ads, internet connections ect. - so they are adept at interpersonal communication. Complete strangers are able to generate conversations in Cuba - they don;'t have that social distance between strangers. People on buses will talk to each other. Whereas here in Toronto I assume anyone that talks to me on the subway to be 'different' or worse (crazy). Talking with Cubans on the street is easy if you have any Spanish skills. They are more than happy to pose for you. Spanish language skills is the most critical issue in making your trip better. You miss out on what is Cuba's biggest asset - people that are social and friendly because they don't have a mass media to cocoon to everyday like we do. More of their lives is spent in the public realm, unlike me or you who may sit in solitude in front of a TV, magazine, newspaper or computer for hours a day. Social interaction is what they do to pass the time away. they are friendly, funny, interesting and engaging.
That said, if you speak nothing beyond 'gracias' and 'por favor' you will still have a great trip.
Can't miss locations? The town of Vinales in Pinar del Rio is a few hours bus trip and has amazing scenery with it's tobacco fields and karst mogote hills. But it is a bit far for a day trip.
In Havana there are great photo ops in the cemetery - a traditional Spanish cemetery similar to the one in Buenos Aires but not as grand or maintained. Havana's harbor is accessible and photo worthy if you like industrial hell and bleak photos. Havana has the well maintained harbour fort called Morro castle that is beautiful, historic and gives great views of the city (morning light is best). The sea wall (Malecon) in the afternoon/evening is a great place for candids of fishermen as well as sunset shots. Bring a cheap bottle of Havana Club rum and a impromptu party of new friends will appear. The Capitolio is interesting inside. Drop by the Hotel Nacional for a drink poolside. Both are photogenic.
Personally I enjoy just walking the streets of Old Havana amongst the crumbling buildings in need of paint.