Watch out for the hotels. They are very pricy and I have a feeling people from another part of Colombia do not pay the same prices that americans or europeans are paying. Try to know some one and they could guide you.
Unique Suggestions: You can negotiate prices on most things so don't settle for what they say.
No doubt Cartagena is the most beautiful city in Colombia. As a result, Cartagena also is the most popular tourist resort town in Colombia. You will encounter those crazy guys trying to sell all those T-shirts, necklaces, Cuban cigars and sunglasses, just like in any other tourist spots.
The picture shows an old postcard of Cartagena