As an English speaker, it is very difficult to learn and apply indirect objects in Spanish.
I understand why you need les in the following sentence. It is because you are making dinner "for them." However is there an easy way to remember this construction when you are actually talking. I seem to understand it when I read it, but don't seem to be able to apply indirect objects when I try to speak. Is this common? How do I overcome it? It is like you are saying for them twice. Once as the pronoun "les" and once as "a nuestros invitados.
Nosotros les preparamos la cena a nuestros invitados.We are cooking dinner for our guests.