My parents went to Colombia a couple weeks back and here are some tips.

For starters keep in mind Colombia is very different from America(assuming you are also American). Colombia is still a third world country so poverty is still very much alive. The first tip is keep all flashy and expensive things at home. If you can do not bring them to Colombia. Smart phones are VERY rare in Colombia so if you have one you will stick out like a sore thumb and you might be a target for kidnapping or robbery. Same goes for things like apple watches and super high tech computers.

Also if you have to use public transport(buses or trains), keep an eye out for your things. Avoid putting your wallet in your back pocket since this is one of the most common ways people are robbed. If you have a backpack keep it with a lock. Additionally if you are being robbed give them your stuff. Most of the time when you try to be a hero, you get stabbed. Second the justice system isn't that great so avoid getting into any kind of trouble. When you go out to night clubs keep an eye on your drink. There is a "new" method of robbing called "el paseo millonario". Basically your drink gets spiked either by a lovely woman or a bar tender then they take you in a cab and try to get you to withdraw all your money or will try to steal all of your stuff.

Try to stay in the "nicer" areas as they are typically well patrolled. If you go to the poorer areas avoid wearing any name brand stuff and try to dress down.

Also Wifi is really hard to come by so if you can carry a hot spot that would help you out if in case you need to communicate with family.

Despite what I listed above Colombia is a wonderful place just always keep your eyes open and if you do not feel comfortable or safe avoid those places.