Cebu is a relatively safe place to be in, killings are quite rare-probably because of the mandatory death penalty associated with it. The most common of crimes that a foreigner might encounter would be theft, which is is not surprising considering that this happens in most third world countries. Theft can happen in a lot of ways. Be sure to watch out for this.
1. While walking in the downtown area, don't wear expensive jewelry and watches. Thieves prey on these people and will often distract you to something with another one snatching your jewelery away from you.
2. When eating at fast food restaurants, don't put your cellphone or wallet on the table. Remember theives work in teams here. One of them will try to engage in a conversation with you while the other will slowly walk pass by and grab your belongings without you even noticing it. I had friends who experienced this and they're were locals, imagine more for a foreigner.
3. Don't talk with your cellphone while walking in the downtown area.