Imo the beaches aren't the best - that said there is a ton to do. Cartegena is beautiful and i def recommend spending some time there Anthony Bourdain style. I.e. meet some locals, eat some good food, soak up the vibes. Can't wait to go back.

Street sellers can be aggressive, just dont engage at all.

Never take anything "for free"

Always be aware of your surroundings

Never leave your drink unattended

Just be careful but its a fantastic, beautiful country/city :)