Avoid walking in the parks alone when it's dark, use your common sense to avoid danger.
Viña del Mar has a big problem with street dogs and many are born in the streets which means that they carry diseases. Avoid touching or giving them food. It can cause you more trouble.
Stay alert, fraud is a most common criminal offense against the tourist. Avoid unofficial currency.
If you get in trouble, ask for help to the police, called "Carabineros de Chile". They wear green uniforms and are very efficient and trustworthy. Don't even think to bribe them or you will go to jail. They are very proud of their creed, and bribing is a serious offense to them.
cope
If you want to use a toilet there are some public ones on the streets and near the beaches but also in restaurants. They charge a fee but most of them are dirty. If you can, ask the staff in the casino if you can use the toilet. Being a foreign tourist will make it easier.
beaches
There are some guards at the beaches but from March to November the beach season is officially over.
Stay near the beach when swimming, most of the people who drown are those who can actually swim. Many of them go out too far and understimate the power of the waves in the area.
Bathing during off-season from March to November is not forbidden, but you're doing it at your own risk. Authorities won't take responsibility if something happens to you or any related.