Guatemala has a bad reputation when it comes to safety. The only news that reaches other countries is often about excessive violence and shootings between drug gangs.
This does not mean that it is impossible to visit Guatemala. 2 million tourists visit Guatemala every year and most of them encounter no problems. Guatemala is too beautiful not to visit.
Even if the numbers of violence are high, almost none of it directed towards tourists. The criminality that a few tourists encounter are mostly because of poverty and not of organized crime. They are desperate people that see this as the only solution to make some money.
In most travel guides have clear instructions to avoid crime. The main advice is:
Use your common sense!