There are several types of offerings which Modern Hellenic Polytheists give to the Gods. The most common are libations, or liquid offerings. These offerings are poured either directly onto the ground or altar fire.
Another common offering is called a votive offering. These offerings can be just about anything but are most commonly candles and incense.
A third kind of offering is called an offering of first-fruit. In this case, the worshipper offers the first goods of the season. For some people this is literally the first fruit or harvest. For others, it can be the first paycheck of a new job.
Finally, a type of offering is animal sacrifice. At this point in time, very few modern Greek Polytheists actually slaughter animals in the name of the Gods. A substitution for the animal is a loaf of bread which is filled with barley or other food. During the ritual, this is broken or cut so that the food inside can come out.