Havana is most probably your first step in Cuba, and is definately worth to spend 2-3 days there, exploring and most of all enjoying the city, since there is not such a long list of sightseeings.
First of all, I strongly encourage you to sleep in a Casa Particulares, meaning in private familiy that rent a room for tourists: you can find amazing colonial houses, a warm welcoming from the family and spend like 35 USD a night. Hotels are usually managed by the government, they are expensive and often the service is awful. Here’s mine in Havana, Casa Colonial 1715, in the heart of Havana Vieja (Old Town). There are other new part of town with a wider choice of houses, and most of them bigger, but if you want to enjoy the life of Havana you should stay in Old Town, also because most of the attractions are around there.
Even if you don’t like cars, you will be amazed by the parade of vintage cars you will find here. Colorful and from another age, you will have the change to have a ride on them around the city, which really make you travel back in time. Always bargain for the price, but better the car, more expensive it is going to be!
Another unmissable sight of Havana are the propaganda wall paintings and posters: since there is no advertising at all, the only form of communication on billboards are about socialism and propaganda. Some of them are really beautiful, and definately better than a McDonald billboard. Hopefully it will stay like this as long as possible.
The propaganda wall painting of Che Guevara is the most common, and I have used it for my project Barbie Around the World, which narrates the travels of the popular doll around the world.
At sunset, the best walk is on the Malecon, a sidewalk that runs from Havana Vieja all along the seaside. You will find a lot of kiosk for mojito, and a nice overview of colonial houses along the road. And this was another spot I used for Barbie and Ken, next to an amazing vintage car.
After all this walking, you have to experience one of the best Mojito in town at La Bodeguida Del Medio, a very very popular historical bar in Havana Vieja. Yes, it is full of tourists, and it is more expensive than others (around 5 euro per mojito), but I believe it as one of the best I’ve tried in Cuba. Don’t stop at one!