Something that might help you is knowing

light clothing

You must bring comfortable and light clothes. Cartagena is very hot, so you must not pack heavy or warm clothing.

You have to ask about prices before you take any service at the beach. If you don't ask first, you might pay too much.

You don't have to spend a lot of money to have a good time. Many places are free, like walking around the walls or visiting Getsemaní.