Don't be stupid is the first rule or guideline. It's also a tenet of satanism but I guess that's beside the point. There isn't really a sure fire way to not get broken heart. In my experience, best case scenario you pick someone whose heart YOU will inevitably break and even then there is a pile of baggage. Just don't make stupid moves when everyone and you, before you got in the relationship, knows are stupid moves. Lovers can convince you to do things you never thought you'd do and in some cases never should do. Keep your wits and don't take love lightly because emotions are stronger than logic.