Safety and security has vastly improved in Colombia in recent years, but there are still inherent dangers. Whatever you do, don't let the rumours and urban legends scare you off.
As in most large cities anywhere in the world, there is street crime in Colombia. You are recommended to avoid carrying large amounts of cash and to keep an eye on your camera and wallet or purse. Wearing jewellery will attract attention of those who may want to take it from you.
Generally, Colombians are surprised and pleased that a foreigner is interested in getting to know their country. It is, therefore, more likely that you will meet welcoming Colombians who are inviting and proud to show their country.
At all times, it is important to keep in mind that you are traveling in a less developed country that continues to deal with social problems. In the eyes of many, you are a tourist with lots of money, so you should always be vigilant. Within a short time of arriving in Colombia, you'll feel your confidence in the security situation quickly growing.