There is no set in stone answer for this.You offer what you feel you should and are capable of doing with a respectable approach. That is always the best route.
You could offer anything really. :/ Doesn't matter what it is, I am sure they would like it either way. They're not going to be eating, drinking, and smoking it anyways.
Greek Gods usually enjoy food offerings and wine. Elaborate rituals aren't normally needed. They also like the use of elements (usually).