If you want to work for a national company, such as Bancolombia/Conavi, Avianca, or Presto, you must be able to speak Spanish with near-native fluency. Depending on your qualifications, companies may offer Spanish lessons, however always make sure that you are indeed eligible for the position advertised. You can teach English for extra money, especially in smaller cities where the demand for it is high. Also you could work for a NGO.
learn salsa
Colombia is one of the mother countries of Salsa and you will be able to listen to this music all over the place. In the last years several of the Salsa World Champions came from Colombia. Especially in Cali and Cartagena there are plenty of clubs and schools.